Between Silk and Cyanide (72 page)

I left for Milton Hall with her chess-set in my briefcase.

Built in the seventeenth century, Milton Hall was a few miles from Peterborough but managed to live it down, and everything about it was sepulchral except for its present inhabitants, who were waiting for me in the lecture room, all of them wearing British, American or French uniforms.

I'd asked Colonel Musgrove not to introduce me and strode to the platform unannounced. Someone laughed, and someone else blew a raspberry (or worse) as I turned to face them, and I knew that if I didn't establish a beach-head with my first sentence, there wouldn't be a second.

I remembered the approach I'd selected on the night of the Bardsea brood: 'Listen, you bastards, if you can remember how to…' Beach-head established.

'… while we're scoring points off each other, an agent in France has only one hope of not being caught, and that's to be picked up by Lysander in the next few hours… would it bore you to know what's stopping us?'

This is the most important talk I've ever given.

'… he's lost his silks, and had to use his poem to give us his pick-up points, but the silly sod's made a mistake in his coding and the bloody thing's indecipherable, indechiffrable, impossible to read…'

Is it the shock of Violette's capture that's made me realize what I must say?

'… two hundred girls are working the clock round to break it, and I should be up there trying to help them instead of pissing around with Jedburghs who've forgotten how to learn…'

Concentrate on the girls.

'… they've already made ten thousand attempts to crack it, and they're on their second ten now, and you might like to know that when you're in France, as you bloody soon will be, we'll do the same for you because we happen to be cunts enough to believe that you're worth it…'

Shoulders back, change tone, the next bit's critical.

'… you've been told that because you'll be wearing uniform, you'll be treated as prisoners of war if you're caught. I don't think you should bank on it…'

Colonel Musgrove stiffened at this because I'd no right to say it. But I'd even less right not to. The first thing they'd be tortured for would be their codes and security checks.

'… if you're caught, you could lie to them about your onetime pads and WOKs, provided you've had the sense to destroy the used portions, but poems are a different matter.'

Stop dreading the next stage or the bastards will pick it up.

'… I'm going to risk turning my back on you because there's something I want you to have a good look at, and I don't mean my arse.'

I took the cover off the blackboard, on which the coding instructress had written two messages of equal length, one on top of the other. 'These are two messages in the same poem-code. I want you to see how the Boche would break them, and they're a bloody sight better at it than I am…'

I'd been dreading this moment because I hadn't shown anyone what I was about to show them. Until now I'd made a parlour-game of poem-cracking, which most audiences enjoyed as much as I did. But these audiences had never included agents, who'd had to make do with warnings as I was afraid that the extra anxiety would make them send even more indecipherables.

Christ, how wrong I was, and how late to find it out.

More and more agents were using their poems because their silks weren't to hand, or because it was more convenient. But we didn't know how the Jedburghs would behave, though the signs were ominous. Their traffic would be equally new to the Germans, who would take great interest in it.

But it would be no good warning this bunch to keep their poems for emergencies; they'd go out of their way to create them. Nor would it be enough to play the parlour-game with them. I had to make brave men frightened to use their poems and risk the indecipherables they'd send us. And the only way to frighten them would be to make them watch the mathematics involved, and show them the technical tricks of the trade, even though they were unlikely to understand them.

Herr von Marks began breaking the two messages without any concessions to the Jedburghs, hoping they'd let him finish. But in the middle of playing a German cryptographer I had a lapse of concentration, and found myself thinking about 'The Life That I Have', and for the first time wished I hadn't written it.

But that wasn't my only lapse. The room was so full of death I began thinking about a conversation I'd heard in the Signals Office concerning a young man who was about to be hanged for murder, and the girls had asked what I thought about capital punishment. I hadn't answered them then but a poem spurted out now:

It's agreed
That a good preventative
Must be neither weak nor tentative
And that the vicious and aberrant
Are in need of a deterrent
But while millions are going under
By design or blunder
Must we claim one more
Just to settle the score?
Shall we really feel safer
When he snaps like a wafer?
Will there never be enough breath about
While there's breath about?
[41]

Glancing at my mental watch, I found I'd overrun by six minutes.

I spared them the interval counts (they'd never know how lucky they were) and five minutes later the code-groups surrendered their texts. I turned round to see the effect. They were staring at the blackboard as if they'd just discovered holes in their bullet-proof vests.

This is the moment for the parlour-game.

I showed them how the Boche reconstructed poems from transposition-keys, and invited them to have a go at the key I'd just broken. They were the noisiest cryptographers I'd met, competing with each other to roar out their suggestions, some of them right.

Keep quiet and let 'em go solo.

They continued Jedburghizing the key for another ten minutes, which was as much as it could take.

I hoped I'd chosen an appropriate quotation: 'They also serve who only stand and wait.' The cheer that went up could have been heard by its author after whom Milton Hall was named (it was the last line of Milton's sonnet on his blindness).

I'll know in the next ten seconds if I've really seen the light.

'Any questions?'

A hand shot up but I couldn't see who owned it.

'Yes, hand?'

'This may be a damn stupid suggestion…'

Christ, a shy Jedburgh.

'Mr Marks… can we do anything to help you break that agent's message?'

An even louder cheer went up, reducing the others to a whisper.

That's the most important question I've ever been asked.

I mumbled my thanks, and undertook to let them know at once if the girls needed help with the keys.

'Any more questions?'

An authoritative voice called out. 'Get back to that indecipherable. You've told us all we need to know.'

I left for London without inspecting the library.

I returned to a summons from Nick, who told me at once that he'd had a call from Colonel Musgrove; he was 'far from displeased by the results of my visit' but had said something which puzzled him.

'… the Jedburghs are pestering him to know if the indecipherable's been broken, and he's interested too. Which message are they talking about?'

'It came in from Emile last week. We broke it on Friday, and he was picked up on Saturday. I pretended we were still working on it because they don't like ancient history.'

He seemed about to comment but changed his mind and announced that I was to keep the whole of tomorrow morning free for a 'very important visitor'.

Still thinking about the Jedburghs, I learned that his name was Commander Denniston, and that he'd been in charge of Bletchley until two years ago.

I woke up sharply. 'Then he knows Tiltman?'

'Knows him?—He was John's boss.'

'I never knew he had one. What's Denniston doing now?'

'That's not your concern. He'll be here at ten o'clock tomorrow, and you're to answer his questions fully.'

'What's he after?'

'He'll tell you himself.' He looked at me critically. 'The commander has no time to waste, so you'd better be on top form for him. Go home early. That's an order.'

He dismissed me before I could question him further.

I sent a message to the Jedburghs: 'Message out, rescue op. mounted, wish you all merde alors.'

I had a feeling that at ten o'clock tomorrow I'd be needing it myself.

'We all need a centre
A core we can rely on
Our private Mount Zion
Which all can see
But none can spy on.'

(Written on the eve of Commander Denniston's visit)

The most unnerving part of Denniston-Day was its tranquil start only eight indecipherables were waiting to be broken, only three agents had lost their silks, and only two lots of codes had been sent to the wrong stations. Better still, there were only three messages from Cairo demanding more WOKs and LOPs, only one request from Melbourne for more briefing officers, and only two agents had used the same WOK-keys twice.

By the time I'd persuaded the latter's country sections to remind them of their instructions it was ten o'clock.

Commander Denniston had an open manner, though every hair of his head seemed shampooed with secrets, and I was relieved to find that I could look a Bletchley wizard in the eye with some sense of parity as he was no taller than I was.

Declining my offer of refreshments—an unpromising start—he said that he'd heard a great deal from Nick and others about the Codes we were using, and wanted to see them for himself.

Longing to ask who the 'others' were, I pointed to the codes on the wall, which he'd already taken in at a glance. 'There they all are, sir. Please help yourself.'

He nodded his acceptance, and I christened his walk the Bletchley two-step.

He had a unique way of examining the silks. He seemed to inhale them like Father testing a Havana for counterfeit leaf, asking me pertinent questions as he passed from one to the other and nodding at my answers (he turned out to be an expert in nod-language). He seemed particularly interested in the code-books (especially the one I'd delivered to the FFI) and asked if much use had been made of them.

I replied that most agents preferred to encode their messages directly on to one-time pads as it took less time.

'That's disappointing—especially as the code-groups reduce Morse mutilation.'

I hadn't pointed this out.

As he put the code-books aside, I was suddenly convinced that I'd done something wrong, and that it wasn't only codes he was here to examine.

WOKs came next. 'Isn't this the system you showed John Tiltman because you needed his blessing before you could use it?'

'Yes, sir. He's their godfather.'

'You couldn't have a better.'

I realized that he knew about Tiltman's visit, and wondered what other homework he'd done.

I wish to Christ I knew what the little sod's after.

He questioned me closely about WOK-production, and wanted to know why we preferred keys made by hand to the machine-made keys supplied by Bletchley.

I explained that Bletchley hadn't produced them in sufficient quantities, and that the ones which they'd sent us didn't seem to me as random as the keys the girls produced by shuffling counters.

He looked at me doubtfully, so I gave him six sheets of keys produced by the girls, and six by Bletchley. He correctly identified Bletchley's, agreed there was a pattern to them, and asked if I'd drawn their attention to it. When I admitted that I hadn't because we were so grateful to Bletchley he suggested that I did so at once as it might be helpful to them.

Surely these are minor matters for a man with no time to waste?

His next comment made me wonder even more what his new job was, and where the hell this was leading.

He said that he'd heard from Nick that I'd devised a deception scheme called Gift-horse. '… I'd like you to explain its function, and then show me some examples.'

I was ready to discuss anything, but Gift-horse was the one subject I wasn't prepared for as Nick rarely enquired about it and I didn't believe that he'd absorbed its technicalities.

'The function of Gift-horse is to make WOK-messages look as if they've been passed in poem-codes to waste the enemy's time, and make our traffic more trouble than it's worth.'

'Method?'

'Without agents knowing it, we repeat the indicator-groups on their WOKs to make it look as if they've used the same keys twice, though they're different every time.'

'Examples?'

I removed twelve Gift-horsed WOKs from the safe and spread them in front of him in silence.

He examined each one carefully, and I could tell from his nod-language that he'd spotted the repeated groups at a glance. I then made the mistake of saying that we also Gift-horsed our dummy traffic.

'What dummy traffic?'

I explained that we transmitted dummy messages round the clock to hide the volume of our real traffic, and without being asked showed him six examples.

Nod nod frown frown nod nod. 'I've two questions about Gifthorse.'

He's letting me off lightly.

'You display Top Secret material on the walls of your office, so why do you keep Gift-horsed WOKs in a safe?'

'To stop me from gloating over them.'

'You've good reason to.'

Then why does his voice have an edge to it?

'My second question's this. Have you discussed Gift-horse with John Tiltman or anyone else at Bletchley Park?'

He could tell at a glance that I hadn't.

'Did you think it wouldn't interest them—or that it was none of their business?'

He didn't wait for an answer, which was just as well as I'd need a year to find one.

'I'll come back to that later.'

If you must.

'I'm going to ask you a question about letter one-time pads, and I want you to consider your answer carefully.'

Safe ground at last.