Tonight in Edinburgh the Take Tea with Turing anthology was launched at Edinburgh’s Informatics Centre, celebrating the life of Alan Turing. This is my piece from the anthology, inspired by Turing’s excellence at running and other questions.

Jessop knocked on the door and poked his red face into the room.

‘Football’s cancelled.’

I propped myself up on the pillow and looked out of the window. When had the fog come down? I guess I’d been nose to book for—two already? I had until six. Football would have filled that gap with time to spare; and I needed to collect my shoes from the cobbler at Kings Gate. I put the book down. My feet were itchy. The run out to Ely was seventeen miles, and back again. I looked at my watch.


A grunt, then footsteps back down the corridor. Red face round the door.

‘What is it?’

‘Tell the guest from—’

‘Alan! Shhh…’ Jessop’s neck disappeared into his shoulders. ‘You’re not meant to—’

‘Calm down, man. Okay, tell Mr Simms I might be a little late for supper.’


There was that fellow again. I’d passed him a few times on the trail somewhere between Dimmock’s Cote and Waterbeach. That week the river at Swaffham Prior burst its banks and the trail was virtually submerged. He was splashing through, having a great time, the muddy duck. Up to his knees. He always smiled and greeted me. I strode on past, it was my fastest section and I wouldn’t slow down.

‘Gentleman Sir!’ he shouted, and gave a mock salute. ‘You’re flying again.’

I never seemed to have breath to reply. How he mustered up the free will to be so god damn friendly I’ll never know. Maybe there was no free will, and he was simply bound by universal law to greet me. Gentleman Sir!, really?

They gave me an awful look at dinner. Mr Simms was all Brylcream and standard-issue cufflinks. Who was he kidding? I managed to avoid them for the most of the night, sticking to the bar and Jessop and keeping one eye on the roving mortar of Battson, who was doing his best as host to keep Simms interested. But I suppose there was no getting away from it. He’d read my thesis, he’d come to meet me.

‘Turing,’ I heard Battson snap at my ear. I jumped and almost dropped my half-and-half. Mr Simms was standing there, fiddling with his tie. Grey and dreary cotton. And next to him, that man from the track, smiling. They were all looking at my feet.

‘Running shoes are not allowed in the dining hall, Turing,’ said Battson, shaking his head.


So it turns out we are not built of grass or cement or seeds, but bricks. We are made of little living bricks. When we grow, these bricks divide—okay, perhaps brick is perhaps the wrong material. But stay with it. How they grow, and where they should be placed, and when they should split again, no-one has worked out. What we know least about is the calculation. Take this example from today. Turned over my ankle, not severely, only a minor torque. The tendonopathy stimulates regenerative growth of tissue, and the body need know how many, where, how fast, to re-grow. What can calculate that? Only the mind—at the moment.

The force of impact of the heel striking the ground is measured in moments. They are called moments of force. I avoid all such moments, or at least try to. They bloody hurt. Most of the time I land on the mid- foot, not the heel. That way the landing is cushioned. The torque is still at the ankle, but rather than, oh, I’d guess 600 body-weights per second going up the leg into the lower spine, it will be around 100 body-weights per second. That’s how I dodge injury, usually: avoid the moments.

Bletchley is a cold, lonely place.

And I have not seen Gentleman Sir!, nor Mr Simms, since I arrived.


‘Off again?’ asked Malcolm. Malcolm opened up Hut 8 in the mornings and turned on the machine and made sure she was running by the time I arrived. He locked up at night. One time I’d found him here on the weekend. Said he’d had a tiff with his wife. I’m sure those things happened.

‘London, Malcolm, yes,’ I said.

He crossed his arms.

‘You’re running there?’

He stood blinking like one of the displays on the left rack. Not the right, for some reason, they had a different pattern. We hadn’t configured that yet. I tied my laces.

‘Yes, Malcolm. How else am I to think?’

‘You could get the train, sir.’

‘Think? On those narrow carriages?’

‘You could go for a jog around the lake, sir.’

I snorted. Oh, the lake! They kept me to laps of the lake. They didn’t let me out far enough to stretch my legs. National Security, really! I stood and stamped my feet.

‘It’s only when I go down to London that I get let off the leash.’

‘You’re a funny one, if you don’t mind me saying, sir.’

‘Keep her running for me Malcolm. And say hello to the wife.’

Twenty and a half miles in I was jumping over the slippery mud track of the canal alongside the Watford Road. It was drenched from the past week’s irascible showers. Hmmph, I thought, I suppose they could think of me that way. I resolved not to chain my mug to the radiator. But that was all! I slipped off the path into bramble. I pulled myself out. Nothing serious. I would shower before dinner. I thought of GS while I ran. Why, I’d not thought of him for months. Gentleman Sir! You’re flying, go on with you. Hardly anyone on the path that day—the downpour saw to that. I waddled through caramel-coloured mud. The ground slipped sideways under each foot landing, from the sagittal to the transverse plane. It was like running on flapping silk. Rather a contradiction. The ground moving as I moved across it, light enough to tear but strong enough to bear me. Leaping across puddles that covered the whole path; jumbling over buried stone; mounds of trodden clay and lichen-covered branches that blew off in the storms and lay in the path like lost crooked legs. Running, it made sense. It was past Hemel Hempstead as I entered Merlin Wood that I knew what I’d tell the brass. I didn’t attend the dinner. I stayed in my room at the Belvoir and wrote until I ran out of lead.

‘The cryptanalytic machine,’ I announced at the next morning’s meeting.

The generals looked less confused than the brigadier. Bless him.

‘The idea that you can use, in effect, a theorem in logic which sounds,’ I hesitated, but why not, god damn them, you’re flying, go on with you, ‘which sounds to the untrained ear absurd; namely that from a contradiction, you can deduce everything.

It took them by surprise. A long silence. Then one of the generals cleared his throat.

‘What the hell do you mean, man?’


It was 1946 when I met Johnny and Chris. I was past those workhorses in ten strides usually, a lunchtime run round the NP. That day Johnny and Chris kept up, slogging through the mud on the back trails. Or tried to keep up, that is; long enough to ask me who I was. I grunted louder. I was a noisy runner. I preferred running alone. Hadn’t I always run to get away from bothersome questions?

‘Come on chap, who—who are you—then?’

‘Nobody,’ I said.

The worst possible answer. They asked me to join Walton AC immediately.


Years before, I’d sat in Hut 8 wiggling my toes in front of me. I’d gotten a callous on a run back from London and had my socks off while working on the prototype. I had my feet up, and for fun pushed at the crib. The rotor settings weren’t connected to the plugboard, so there was no threat of breaking the damn thing. But wouldn’t you know it, that was the only day GS came to visit. Surprised me. Said his name was Frankie. That was all: Frankie.

‘Always create with your shoes off?’ he asked, smiling.

He wanted to know how the bombe worked. For each possible setting of the rotors, I told him, which had of the order of 1019 states, or 1022 for the four-rotor U-boat variant,the bombe performed a chain of logical deductions based on the crib, implemented electrically. The bombe detected when a contradiction had occurred, and ruled out that setting, moving on to the next.

He had his arms crossed. He was nodding too fast to know what on earth I was talking about. He looked at me. It was rather a sly look, I thought.

‘And it’s foot-operated?’ he asked, one eyebrow raised.


Johnny was leaning against the post by the Milton Country Park gate. We’d just done our Sunday twenty. I was out of sorts that day. That’s why Johnny looked so flushed: he’d been able to keep up. It was ’49 I think. After the Triple As. I’d lost motivation. I remember he and Chris were laughing as we packed up. Then from his bag Johnny pulled out that five pound note I’d given him before the boys went over on the ferry for the Nijmegen marathon.

‘Here,’ said Johnny, ‘I said I’d give it back.’

‘It was for the drinks after the race,’ I told him.

‘Guilt money, more like,’ said Chris.

I pulled on my tank top, and somehow ripped a hole in the side.

‘God damn! What do you mean by that, Chris?’ I snapped.

‘I meant you should have come with us,’ said Chris, stuffing his vest into his bag. ‘You should have raced.’ He stared at me as if I were some horrible creature. ‘The war’s over you know, Alan.’ He walked off.

I threw my bag over my shoulder.

‘I think you’re a little too stern with Chris,’ said Johnny.

‘I think you should have brought me back some clogs.’

‘To run in?’ Johnny laughed.

We started walking after Chris. Johnny thrust the fiver under my nose.

I waved him away. ‘I don’t need it. Keep it.’

Johnny frowned. Then he put the money back into his bag. We walked for a while in silence, back to the pub. Just the gravel under out feet.

‘Why do you punish yourself so much, Alan?’ asked Johnny, rather out of the blue.

Had I let the boys down? Fifth at the Triple As was not shabby. Only ten minutes off Olympic pace. I supposed it was a classic halting problem. Given a description of an arbitrary program, decide whether the program finishes running or continues to run forever. I thought I’d solved that back in 1936. It wasn’t possible. But that was all done with now. I never wanted to dedicate a life to running. I never wanted it to become an obsession. I put a hand on Johnny’s shoulder.

‘Sorry about Chris. I have such a stressful job that the only way I can get it out of my mind is by running hard. It’s the only way I can get some release.’


A machine is a device that manipulates symbols on a strip of tape. Through simple instructions—move forward, erase, write, read, my machine can enact any algorithm.

But not every algorithm has a machine to run it.

What if I’d never stopped running? What if I’d said ‘Gentlemen Sir! to you too?’

Well, it would have all been over a lot earlier than it was.

Think of running as a strip of tape. Move forward, left, jump, halt. Race. Erase. A computer, it turns out, is just a particular kind of machine that works by pretending to be another machine: a calculator, a ledger, a typewriter, a code-breaker.

But not a runner. A runner doesn’t pretend. He’s nothing other than what he is.

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