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Tommy Flowers and the Glass Bells of Bletchley

When little Tommy Flowers was presented with a baby sister, he was disappointed to find that she was not a Meccano set. Her head lacked the simple geometry of strips and cogs and angle girders, and her fingers were innocent of gears. What was worse was the fact that she cried so—wailed, really, and nothing comprehensible at that. There was nowhere for him to build in peace, and even the construction sets he did have paled when he couldn’t hear their connective clicks for crying.

If he could have used his dad’s bricks to build a wall between himself and the cot he would have. “You wouldn’t be able to hear her if you did that,” said his dad, bringing him a glass of milk and an apple for his supper, and that was the point.

“It’s not like she can talk, is it,” said Tommy. “So I wouldn’t be missing out on much.”

“She’s talking,” said his dad. “In her own way. It don’t sound like much now, but you’ll figure it out.”

Tommy bolted plates together, tightening the nuts carefully, with deliberation, a milk moustache on his face. The empty glass sat beside him, near clear but for the last pale drops slithering to the bottom. He lay on his tummy, cogs around him, and when his sister squawked from her place in her cot, he glanced at her, automatically, through the smeared material of glass.

It was in his way. He couldn’t help it.

What are you doing? said the glass. The milk drops had coalesced, moving upwards, forming wet, sloppy letters on the inside of the glass—letters that soon lost their form and dribbled down into disassembled alphabets.

The glass wasn’t warm, or cold. Tommy snatched it up to his ear, but it didn’t make any sort of sound, and when he put his finger in, gingerly, and then his tongue, the drips of milk remaining didn’t taste any different that they usually did.

His sister squawked again, interrogative.

What are you doing? said the glass. Tommy had cleaned out most of the remaining milk with his tongue, so the letters were much fainter than before. He looked at his sister, and she looked back, her head cocked on one side and fat, gearless fingers gripping the bars of the cot in fascinated earnest.

“I’m building,” he said, feeling stupid. He didn’t say it very loudly, in case he was going crazy, in which case it would be best if dad didn’t hear him, but he said it nonetheless. He reached out with one hand, blind, and felt a girder piece press into one palm. “Look,” he said, waving it at his sister. “You make the pieces fit together. For trains, and cranes, and . . . all sorts.”

His sister gave a little chirrup.

Can I have a train? said his milk glass, and Tommy resigned himself to building to order, and to a baby that stumbled after him through the house, clutching a milk bottle that bubbled What are you doing, Tommy? What are you doing? What are you doing?

He has an affinity for glass.

This is not always a positive thing. He gets through his apprenticeship alright, but the night classes for engineering are more difficult. The windows always want to tell him answers, though he’s saved from temptation by the fact that he can’t hold a test paper up to them without a proctor noticing. He does wear glasses, though, and if he were a lesser man he’d wear them during exams, stifle the small sounds that have started to come with communication, the peeps and peals that ring in his ears like tiny bells, like telephones. Instead, he leaves them off and crouches over the paper until his eyes are only inches off it. Anything else is dishonourable. It would be cheating.

The work pays off, and he’s into the Post Office, in their engineering branch, and he has as much glass to play with as he wants. It comes in the form of vacuum tubes, of valves, and Tommy works on telephone connections, on switchboards, and there are relays in them that are less competent than glass. He builds one with valves, to show it can be done.

Then the war comes, and Hitler’s on the prowl, and Tommy is taken off his switchboards, sent from the research station at Dollis Hill to Buckinghamshire, to Bletchley Park. He is met by a man called Turing, who thinks in algorithms as Tommy thinks in glass, and they meet in a circle of programming and codes.

Turing wants a relay-based machine to help with decoding. Something to supplement the Bombe he already has, something to turn disembowelled alphabet into language. And there is the Heath Robinson, an infernal contraption too slow for Flowers, a cartoon effort he thinks. But when he looks at it he sees switchboards, and glass, and he goes to Turing, then, and tells him he can make something better.

The only other option is him standing over messages as they come in, holding a magnifying glass or a bottle bottom, and he can’t do that. There are too many messages, too many intercepted communications, and he can’t stand in one place every hour of the day until the war ends, in however many years that is. It would be thing if they knew which messages were important and which weren’t, but there’s nothing separating gossip from high command, nothing separating sad and lonely operators (“I’m so lonely,” one sends, far off on the front) from plans and troop movements and ammunition sites.

It’s too much.

Dollis Hill, and Tommy is a member of the Home Guard. It could be worse—his position and his passion have coincided, and he is at the front of nothing but research, of engineering and mathematics and circuits, of vacuum tubes and the giant, sprawling machine that is Colossus, kept dreaming in stages and apart. Even so, his own front is not untouched. There are V2 rockets that miss the laboratory, miss by fractions, incendiary bombs and explosions and the threat of parachutists dropping from the sky and behind the lines like poisoned mayflies.

So he is a member of the Home Guard, and wears his uniform and does his training with the rest, with Speight who gets caught in a blast and walks away unscathed, with Coombs who runs to the roof when the air sirens go off, shouting for bandits and looking for fires. It is terrible, in its way, but there is something exciting in the training, only eight miles as they are from the centre of London and vulnerable to any attack. Tommy half expects one each moment, but when a grenade goes off during an exercise it’s his own side that leaves him with a face full of blood and splinters, little plastic shards from the casing that somehow, somehow, in the smoke and the flash-bang of it, have missed his eyes.

Blood is dripping onto his uniform and his head is bent back under bright lights, cloths pressed to it to stop the bleeding and there is tweezers and rubbing alcohol and a tot of the more palatable stuff, rationed out because he looks a wreck. “Thank God I didn’t lose my sight,” he says, and the mug is shaking in his hand. “Thank God I’m not blind.” Because the circuits need him, and Colossus needs him, and if he cannot build a machine to break the Lorenz then he is no use, no use at all and he might as well be at the front, an obstacle to trip over instead of tripping himself.

When he’s all patched up and dizzier from the relief of it than he was at the feel of blood on his cuffs, he puts on his glasses, fingers heated and slick-sweaty, and inspects himself in the nearest mirror. The door is shut firmly behind him. The damage doesn’t seem too great—one or two of the deeper cuts might scar, he’s not sure, but the lenses are vibrating in their thick frames, and all he can hear, in the silence of the wash room, are tiny round and shrieking screams that crack the mirror all across—crack it in cobwebbed, spidery letters that say blood a thousand times over, and backwards.

Tommy realises, then, the though the mirror is broken it is his glasses that are writing over themselves, coding experience into crystalline structures and he snatches them off, stuffs them deep into his pockets where no-one can see them and only his fingertips, pressed against the lenses, can feel the words bursting like bubbles against his skin; a vitreous, panicky Braille.

“We should be using valves,” he says, and no-one believes him because valves are glass and filaments. They are like light bulbs, and those blow too often and too easily for code-breaking. He doesn’t blame them for their scepticism. A lifetime of bulbs that write Burn! on their insides just as they blow, just as the filaments heat to snapping, that write Burn! with a deep bass note that only Tommy can hear, deep enough that it sets his ears to itching, is enough for any scepticism.

(He can just imagine the valves, all sixteen hundred of them and eight hundred more after that, oxidising in relays, one after the other; how their bright brief words would spark, for a moment. How they’d chime like bells until his chest was breaking with them, until his bones were buzzing.)

“Do you want to be the one who has to change them?” he is asked, and Tommy shakes his head.

“We couldn’t be turning them on and off,” he says. “Like they’re radar, like they’re radio receivers. That’d do for them for certain. We should be using valves, and we’ve got to keep them on.”

He gets his way, and when the Colossi are made they hum the war through, and aren’t switched off till it’s over. He can see the valves all tucked into each machine, each of his perfect giants, and their little glass shapes are stacked in racks, hundreds of them, thousands, clear and bright and he doesn’t look at them too closely once they’re wired in, lest they get ideas and want to show him how they burn.

(If they burn, then more burning will come and it will be more than bulbs, more than message tape. It will be incendiaries and bombs and the boys at the front with white phosphorus and flesh that cannot be put out, flesh that will burn out like filaments.)

(He has to keep them steady. He has to keep them from burning out.)

He gets his way, and the glass is quiet and unburnt, the filaments like stilled clappers, and it’s peaceful, momentarily, if he only looks at them sideways, but too little attention and they’d be clamouring for him in other ways.

“Apple, Butter, Charlie, Damn . . . ” they write, in tiny letters and tiny pulses, muted, pastel in their tones. They’re reaching out, he thinks, wanting attention and picking up words from the Wrens and the windows, from all the glass between them and the Bombes.

“I don’t want to know,” he says to them, all alone of a night, and it’s harsh but he has become a harsh man, sometimes, and no matter that they try to be friendly. There’s a war on, don’t they know.

“He doesn’t care how many of the bloody things he uses.”

Tommy’s heard it more than once, and they’re not wrong. He needs thousands of vacuum tubes for the Colossi, thousands of the bulbs that ring like bells, and there’s always one in his pocket, or in his desk drawer, or fallen under the seat of his car and he’s so used to the sound of chimes around him that they’re part of the background now, like drills and bombs and secrets. He shouldn’t be so reckless with them, he knows, but they’re friendly under his fingers and he’s sick to death of rationing and Churchill himself has given the priority. Besides, it all pays off when the Mark 1 is moved from Dollis Hill to Bletchley, moved in pieces and rebuilt to break the code set for it almost immediately, while people are still interested enough to watch, hanging around and arguing over whether or not it will work.

But it does work, and test-breaks a known code in ten minutes. Tommy will find, later, that this is not the norm. Sometimes Colossus needs hours, not minutes, but on this its first day the machine puts its best shift-registered, clanking foot forward, and the glass chimes quietly to itself, and the cryptographers stand about it with their mouths open, around the giant machine that Tommy admits looks a joke, a thing of string and sealing wax and sound, but it works and he is vindicated in his valves.

He is driving home, after, in chilly February, driving when the car breaks down, sputters to a stop in the road. It is a little splash of sleet against his triumph. Only the beginning, says the windshield, and Tommy’s not sure if this is warning or encouragement or both, but it hasn’t escaped him that he’s built an electronic computer, the first of its kind, and now he’s stuck shivering his backside off, in his shirtsleeves and tinkering under the hood of the car like a kid with his first spanner. “I know, I know,” he says, on his way back to Dollis for the rest of them, for design and improvements and the Mark 2, and the windshield wipers scraping off the frosted fonts, the encumbrances of vision.

There’s a long way to go yet, says the windshield, between swipes, and in his pocket he can feel a vacuum tube pealing its agreement in a soft B flat.

They’ve each got their own voices, and the huts and brick blocks that house the code-breakers of Bletchley sound as much sometimes like barnyards as they do church bells. It’s not only the vacuum tubes—Colossus has more glass than that. There’s the large lamp for looking at paper tapes, and magnifying lenses, and each has their own sound, their own way of writing. The thermionic valves are gaseous, and the bulbs are briefly bright with letters, then words . . . and the codes break open before them, the Lorenz opened up like tin cans and church yards, and Colossus paints itself with cargo lists and commandants and orders.

Komme ich klar, one fragment reads, and the glass lights up, tinkling. Komme ich klar komme ich klar komme ich klar do you see, Tommy?

Yes, thinks Tommy, you are and I do.

“I think it’s whistling at me,” one of the Wrens says to him, giggling. Her hair is damp, plastered to the nape of her neck in little curls, her uniform blouse clinging in the heat. She smells faintly of French chalk and warm glue, the sticky mix invented to loop the paper strips together with prayers and clamping. Behind her, the Colossus rattles and whirs, message tapes rolling at high speed, circling round the bedstead frame.

The valves are conspicuously silent. Tommy doesn’t trust them an inch. “Maybe it’s one of the officers,” he says, not very hopefully.

“I wouldn’t put it past them,” she says, as if someone hadn’t suggested that the Wrens do their work topless, all the better to cope with the vacuum tubes, blazing like a thousand lights and giving off the heat of a hundred electric fires. “But unless that duty officer out there has started whistling in fifths, then I wouldn’t bet money on it.”

There is nothing to do but apologise, and trust that the valves can be intimidated by a savage look. It is a trust that is not repaid. They flicker and giggle for praise, a squeaky carillon just at the edge of hearing, and their bulbous ends illuminate with little sparks of See? See? as the code rolls round.

“I see,” says Tommy. “You’re doing well, you are.” And the Colossus is: five thousand characters a second, and ciphers letting down like milk, like the letters in his sister’s bottle that was. Some of the codes are more difficult than others, and the room has been decorated with daffodils for celebration of a particularly tricky crack. Tommy picks one from where it has been tucked in next to the machine, away from the heat and moving parts. “But don’t get too cocky. We’re not done yet.”

The valves ring at him, deep rolling chimes like sulky purring, and the message tapes move faster, skitter round until they snap and the roll is off its frame and sifting through the room like confetti, rolling over the floor in big, spoilt spirals and that’s it until the Wrens can wind it up and paste it back together, stick it back onto the bedstead.

“You look like you need to cool off,” says the one who had spoken to him before. She is on her knees and winding and making up to the duty officer crouched beside her like he could, indeed, whistle as if he were all the bells at Bletchley. “There’s a water tank outside. Go splash some on your face. Go on, do. You look all red, like a crab apple.”

“It’s not funny,” says Tommy.

“Do I look like I’m laughing?” she says.

Then there’s Mark 2, and Tommy isn’t laughing either, because security is tighter and the Lorenz now has less depths and limits that are beyond them, almost, and they are fishing now more than ever for the key to Tunny, for the keys to all the fish codes of Germany, swimming through the air with the scales too transparent for glass, even. So there is working and eating and sleeping and nothing else for months on end, and not even that much of the last two, and Tommy has wheel patterns to break and the new Colossus has a panel for the breaking.

It’s always hurry, hurry, hurry, and people come down from Bletchley to Dollis to get him to hurry up, damn it, but Tommy’s working as fast as he can and they leave with fleas in their ears after seeing the monstrous application of engines hidden behind the Post Office facade, and then there is understanding as well as haste.

This time there is no testing in London. The whole thing is shipped to Bletchley, shipped in crates and lorries and they set it up right where it’s wanted and hope for the best.

The best doesn’t come. The Mark 2 won’t work, and if Tommy can hear the clatter of the first Colossus in the background, the one that isn’t quite good enough, the one that hasn’t got its hook baited just right, then it makes no difference. It’s the middle of the night, and Tommy is tired, so tired, and his engineers can barely keep themselves upright. He leans against the frame, gently so as not to crush the glass, and it pulses at him. Chandler, the tubes throb, in muted tones. Chandler. For a moment, Tommy is jealous. The Colossi are his babies, his creations, and to have them call for another is rank ingratitude at best, but when he looks around the room, looks at the men so frustrated they’re almost weeping with effort, he knows that he’s not in it alone.

For Chandler is there with him, blinking, dazed, and the fault may be in the section he designed, so Tommy goes to bed and makes everyone else go too, just for a few hours. He leaves Chandler there to think in peace, and it’s enough. When Tommy comes back of a morning, the Mark 2 is running, though everyone has to wear gumboots because there’s a leak in one of the radiator pipes and a puddle spreading towards Colossus. The Wrens are there too, heavy-footed in rubber as they reel and wind, and the machine has met, by bare minutes, its deadline.

“I knew you could do it,” he says to Chandler, who wears a soppy grin and is positively silly with fatigue. Behind them both, the tubes and lamps and lenses gleam, bright like fish hooks, happy and ready for hunting.

Less than a week later, it is D Day.

No bigger than a fist. The war is over, but secrets hold regardless and Tommy is left silent behind a signature of his own making, behind walls and Acts and staring at hands that are useless, in their way, against this new attack. The order has come down, and the Colossi are to be destroyed, all but two of them. Break them down, says Churchill, tear them apart so nothing bigger than a fist is left. So there’s nothing left that can be remade, that can be put back together.

It is the order of a man who has understood cryptography but not science, a man more versed in memory than machines . . . and a man who does not speak to glass.

It is hard for him, hard. Tommy stands in the wreckage, the vacuum tubes broken about his feet, the little shards of valve silenced as bells are silenced when their clappers are taken away. Some of the pieces still buzz, faintly, and half-letters lie in fragments. Worse, there are bulbs that remain intact—the odd one that’s escaped the boot, and the banks on the two Colossi selected to survive. He can hear them, and they are more like sirens now than bells, a high electric pulse. What are you doing, Tommy?

“Can’t you shut those things up?” someone bellows from outside, and Tommy kneels down, then, amidst the wreckage, with his hands flat on the floor, and he can feel the glass prick through his trouser legs, feel it spark into his palms, wet with regret, and all the little pieces are so much smaller than his fist.

“That’s enough now,” he says. “Hush now, that’s enough.”

The boiler back at Dollis Hill is stoked to red-heat. He has the drawings and plans and blue-prints as well, in those same fists, and it’s a struggle not to look at them. He knows these plans—wrote many of them—but how much will he remember when they’re not at his fingertips and the bitter spike of adrenaline, like bloody glass in his mouth, is gone? Part of him wants to read it all over again, one last time before he turns the paper to ashes and the ghosts of bad decisions, and part of him turns his head away, knowing that the fragments he sees will haunt him until he drives himself mad in memories and forbidden reconstruction.

He burns his work, all of it, and the glass shards buried in his fists are buzzing. He can’t even hear them over the roar of the boiler, but he knows what they’re saying, what they’re trying to write on his bones, on the very marrow of his flesh.

What are you doing, Tommy? What are you doing?

When it’s all over, he takes the thousand pounds given to him by the government in compensation for his secrecy and his silence, and it’s not compensation really because he’s spent more than that of his own on the machines he’s just destroyed, but he takes it, and goes down to the nearest pub, with his hands still smeared with blood, and nurses a pint until closing time.

“You alright, mate?” the publican says to him. “You look a bit lost, you do.”

“Fine,” says Tommy. “I’m fine.” There is nothing else to say, and the beer glass is sudsy and silent.

His sister waited every day, squirming with excitement, for the milk cart, but Tommy preferred the postman. He liked the organisation of it—how, with a few short lines, a message could be brought to his house exactly, his house and no other, no matter where in the world it was sent from. Tommy dearly would have liked to receive a letter from Australia, or South Africa, or Argentina. He never did, but if he had it would arrive just the same, a small combination of letters directing the envelope to the correct square mile, the correct square yard, of his own front door step. He didn’t know how many door steps there were in the world but it was a lot. He could walk round the East End all day and his legs would be tired long before he saw every door, and there were a great many more houses outside Poplar—outside London, even.

Getting the right one on the first try was as good as magic. Each day, he waited on the doorstep and waited for the magic to happen.

“Here’s your lot,” said the postman one day, in his peaked hat, in dark blue trousers with a red stripe down each side. (Tommy wanted trousers like that very badly.) The postman had another letter in his hand. “I think this one’s yours, too,” he said, though he didn’t sound very sure of himself. “If it’s not, just give it me next time we see each other, there’s a good lad.”

The address on the envelope was written remarkably poorly. Tommy was good with his letters, most of the time, but even if the ink weren’t all smudged he thought he would have difficulty deciphering it.

“God save us, not again,” said his dad. “Would you look at that chicken scratch! How does she expect me to read it? How does she expect me to reply?”

“You’ve just got to make do, dad,” said Tommy, who’d been told that often enough himself, when there were new Meccano sets out that he’d like to get but couldn’t. It was immensely satisfying to tell someone else to do so. He understood, now, why his dad said it so often.

“That’s alright for you to say,” said his dad. “Either her youngest has toothache or she’s asking for the name of a good haberdasher, like I’d know.”

“Can I have a go?” said Tommy, and when his dad gave him the letter, all funny and scribbled like the hieroglyphs must be on the pyramids, he shut himself up in his room with a magnifying glass. The writing got bigger and madder, but when he breathed on the surface of the glass letters began to form. When he wiped them away with his shirtsleeve they disappeared, but they’d come back when he breathed on the glass again.

“No luck?” his dad said later, and Tommy blushed and said, “No, dad, I can’t read it.” He didn’t like to lie, but it was wrong to read other people’s mail when they thought it was private. He shouldn’t have done it. His dad wouldn’t have given him the letter if he’d thought that Tommy could read it.

Liar, said the magnifying glass, when next he used it. Liar.   

About the Author

Octavia Cade is a New Zealand writer. She’s sold around sixty stories to markets including Clarkesworld, F&SF, and Asimov’s. She’s a Bram Stoker nominee and four time Sir Julius Vogel award winner, and was the 2020 visiting writer in residence at Massey University. Her latest book, the climate fiction novella The Impossible Resurrection of Grief, came out recently from Stelliform.