There were clearly any number of insecure things that could be done with the help of a chocolate-coated wafer bar, twelve brass screws, and a mirror. Already the possible explanations had proliferated to an extent which made critical assessment almost impossible. Then on Beanday Goldwasser had been to a cinema club to see Pudovkin’s Mother, and then to an Odeon to see Charlie’s Aunt, after which he had gone to an Indian restaurant and ordered a chicken biriani, a bhindi ghosht, and three poppadoms.

Nunn’s mind reeled. Why had Goldwasser twice scratched his head in the same place? Who was Pudovkin’s mother? Why three poppadoms, and not two, or four? There were rational answers to these questions. There was, somewhere, a pattern in which twelve brass screws, two head-scratchings, and three poppadoms had their place. There had to be a pattern. The whole possibility of intelligence work depended upon there being a definite natural order in the universe, a discoverable pattern behind the reports which the Jurgensens and Bissels submitted.

The most suggestive report was one dated Teaday, which recorded that at 1300 hours precisely Goldwasser had emerged from his laboratory, stopped in the corridor to scratch his head, and then left the building, to return ten minutes later carrying a picnic lunch which he had consumed at his desk.

Why should Goldwasser stop so deliberately to scratch his head? Normally a man wishing to scratch his head in those circumstances would do it in private, before leaving his room, or if caught short by an urgent desire to scratch it as he walked along the corridor, would try to do it inconspicuously as he went along. And why had Goldwasser eaten a ‘picnic lunch?’ And why at 1300 hours? Because, good God, wasn’t 1300 hours one o’clock in the morning? Nunn had never been able to remember which way round the twenty-four-hour clock was. But he was pretty damned sure 1300 hours was 1 a.m.! In fact he was absolutely certain it was! A so-called picnic lunch consumed at dead of night! What in the name of heaven could it mean?

Nunn stared at the report, his brain overwhelmed by the immensity of the information it was going to yield up to him. He pulled his Compleat Angler’s Diary towards him and wrote on it in large letters:

MIDNIGHT LUNCH

He underlined it. Then he wrote underneath in slightly smaller letters:

Ironmonger—3 poppadoms

Then he tore the page out and burned it in the ashtray for security reasons.

On a fresh page he began to construct a graph showing the daily frequency of Goldwasser’s head-scratching against his consumption of chocolate wafers in the Tea Room, marking on the line the Ironmonger and Midnight Lunch incidents under the code-names SEAHORSE and OVERMANTEL.

He stared at it until it blurred before his eyes. Perhaps he had confused the code-words, and Beanday was Monday and Spoonday was Friday. Or was Troutday Monday, and Plumday Tuesday, and Spoonday Thursday? Or had he just forgotten the days of the week? How the devil did they go? Sunday, Plumday, Tuesday, Spoonday . . . ? Plumday, Monday, Spoonday, Bensday . . . ? Bensday? What was this nonsense? Wumsday, for heaven’s sake.