Between Silk and Cyanide (34 page)

On the night of the 22nd Cammaerts the plodder (code-named Roger) lumbered into a Lysander with his fellow agent Dubourdin and they were deposited in France a few hours later. Their places in the Lysander were at once taken by Peter Churchill and Henri Frager, who were shuttled back to London to have breakfast with Buckmaster!

While all this was happening the code department was a Maquis no one wanted to supply.

The transposition-keys which Tiltman had offered to produce by machine at Bletchley had finally arrived and were a great disappointment. There were long spaces between each pair of keys which would make them difficult to photograph, and I'd found mistakes in several where numbers had been duplicated. Nor were the key-lengths sufficiently varied. The six WOK-makers were doing a better job by hand.

An even greater disappointment was the non-arrival of Tiltman's assistant who'd be responsible for mass-producing the keys. I was anxious to get his reactions to letter one-time pads, which I regarded as my bid for legitimacy in a world full of bastards. It was now essential for my concept of substituting letters for figures to be vetted by an expert. Without Bletchley's approval, I couldn't proceed with it.

The system would also need Nick's support. I'd explained it to him a week ago and he'd promised to think it over, but I hadn't heard from him since. I was about to break his door down when his secretary phoned me. Nick wanted to see me immediately. Tiltman's assistant would be arriving in an hour, and it was essential that we discussed the agenda.

A Lysander couldn't have got me there more quickly.

The moment I crossed Nick's sacrosanct threshold I knew that I'd summoned to a
conférence extraordinaire.

He and Heffer were so immersed in a letter one-time pad that its proud daddy had been obliged to knock twice to gain admittance. They were examining the fledgling code as if unable to decide whether christen or circumcize it.

Pointing to a chair without looking up, Nicky brusquely informed me that he'd explained the system to CD and Gubbins, who were very impressed by its simplicity. However, they insisted that it mustn't be used without Bletchley's blessing. '… which you mustn't count on getting. They may have reservations about one-time pads for agents.'

I didn't need to ask why. If the Germans copied the idea, Bletchley could no longer break the codes of their trainee agents when they transmitted practice messages which Y intercepted. (The agents used the same codes when they landed in England as they did at training school.)

'Marks are you listening to me?
We must settle what you're going (Commander Dudley-Smith.' He pointed out that the commander couldn't spend long with me as he had another appointment, and that he was expecting to discuss the volume of machine-made keys we'd need from Bletchley over the next few months. He then warned me that the commander was 'exceptionally bright', and was likely to ask me some awkward questions. On no account must I disclose the code requirements of individual country sections, or allow myself to be drawn into discussing SOE's future commitments. 'Is that understood?'

'Yes sir' I nearly said 'only too well'.

Bletchley worked closely with C, and the less the 'bastards of Broadway' knew about our plans for expansion the better our chances of survival.

'And there's one other thing. Heffer and I don't insist on this but neither of us think you should discuss one-time pads with him -' He turned to Heffer for confirmation.

The Guru looked at me thoughtfully. 'The timing's wrong,' he said.

He then explained between puffs that letter one-time pads were an important new concept but their use by SOE might involve Bletchley in a conflict of interests, and I'd be well advised not to refer to them until a special meeting could be arranged with Tiltman present.

The wizard of Bletchley had been present ever since I'd met him, but Heffer misread my expression. 'I need hardly remind you,' he said, doing just that, 'that
he
is SOE's coding adviser, that he
did
support your concept of WOKs, and that if letter-pads make Bletchley's task more difficult, then the least we can do is…'

I switched off at this point because I'd prefer to see German agents sitting in the War Cabinet or even running 84 than allow SOE's agents to be deprived of LOPs for a day longer than was absolutely necessary, providing that the system had no flaws.

Nick pointed his finger at me as if he didn't want it back. 'You must learn to concentrate on one code at a time, and "WOKs are more than good enough to be going on with.'

But good enough wasn't good enough if we could produce something better, though I had the sense not to say so.

Thirty minutes later my visitor arrived.

Nick was right in saying that Commander Dudley Smith was 'exceptionally bright'. His gold braid glistened, his eyes sparkled and his mind was a torpedo looking for a target.

Firing practice began at once. He regretted he couldn't lunch with me, as he'd heard 'excellent accounts of Baker Street cuisine', but he'd be glad of some coffee if we had any going (it was already on its way). He congratulated me on the charts for breaking indecipherables which I'd shown Tiltman, and was then kind enough to explain the various uses to which Bletchley put them, none of which had even occurred to me, though I nodded knowingly. It was a subtle way of reminding me that amateurs don't belong in the same ring as proffessionals. His round on points.

I returned the compliment by thanking him for Bletchley's machine-made keys, and he at once asked what was wrong with them.

I decided not to dissimulate until it was absolutely necessary, and pointed out that the long spaces between the keys would make them difficult to reproduce. I also pointed out some mistakes in them, including duplicated numbers. He thanked me for bringing them to attention and assured me that the mistakes wouldn't occur again, at which point I began to suspect that they were deliberate.

He asked whether country sections shared their forward-planning with the Signals directorate, and I replied that as far as I could see they had none to share.

I was saved from further questions by the arrival of the coffee and black-market sandwiches.

I waited until he was involved with the problem of selection before presenting the bill: 'Commander, I've a favour to ask.'

'Go ahead,' he said with smoked-Salmon-induced euphoria.

I told him that I'd been working on a new code which I hadn't thought of when Tiltman was here. Could he possibly spare the time to discuss it with me?

He said that he'd be glad to help in any way he could, though it might be better if I waited for Tiltman's next visit.

'I'd value your opinion, Commander.'

'What sort of code is it?' he enquired with ill-concealed reluctance.

He stopped chewing when I said it was a new form of one-time pad which used letters instead of figures and required no code-book.

I produced a LOP which Joan Dodd had managed to have printed on silk as a very special favour.

'Brief me as if I were an agent,' he said, 'or a country section head.' He sat next to me just as Tiltman had when we broke Skinnarland's indecipherable.

I asked him to choose a message but he preferred to leave it to me. '"Long live Tiltman"?' I suggested.

'I second that,' he said.

I've preferred 'Vivat Tiltman' to show off my Latin, but I wanted a phrase at least fifteen letters long.

I asked him to copy out the first fifteen letters of his one-time pad and write our benediction beneath them.

His handwriting was a flotilla of small ships setting out for Dunkirk. Twelve seconds later (it was important to time him) he completed the first part of his message.

'You now have to encode each pair of letters in turn, starting with the first pair O over L, and ending with the last J over N…'

'How do I do that.?' he asked, as if his future depended on it.

'With the help of a substitution square, which may look complicated but couldn't be simpler.'

I produced one for him.