Their car turned onto the Embankment from Beaufort Street, the reddening sun casting shadows from the pillars of Battersea, then Albert Bridge. Morahan watched joggers evenly, rhythmically striding beside the river and fought for air against the seatbelt entrapping him. The accompanying note insisted that the ‘simple yes or no’ should be given by midnight. He tried to work out why ‘Sayyid’ was granting so little time. Did he know that Morahan would be occupied this evening in chit-chat with whatever members of the do-gooding plutocracy his wife had lined up at their table? That he would have no time to consult or discuss – even if he could have found anyone with whom to share? He flicked a look at Iona. They survived – and, in their ways, prospered – because they had decided at the crossroads in their lives that there would be no secrets in the alliance they would forge. But not tonight. Too soon. Too – how could he put it? – too baffling; too improbable that he, of all people, was entering into a secret world of ‘dead letter boxes’ and heaven knows what else.

‘Sayyid’ was asking him to act alone, to operate outside the system. The request flew in the face of the orderly due process by which, rightly in his view, he conducted his business. Yet, there was something about the letter which made him believe it was important. It felt not just cowardly but wrong to reject it – whether by logging it (he was sure Sayyid meant what he said and somehow had the means to know) or by failing to follow its instructions.

He considered the name ‘Sayyid’. He’d had no time to check its meaning – perhaps it was just to indicate inside knowledge of the world he was entering. He would look it up later.

They were home by 11 p.m. He escorted his wife from car to front door and unlocked it to usher her in. Instead of following her upstairs, he headed towards the kitchen.

‘Just remembered I’ve a letter to post,’ he shouted up.

‘Can’t it wait till morning?’

‘I rather need some air.’

‘Well, try not to squeak that floorboard.’

He tore a strip off a cellophane roll, retreated along the passage to his study, found a sheet of paper and wrote ‘Yes’ on it. He folded it into an envelope and wrapped the cellophane around it. Back in the hall, he removed the bow tie and black jacket and put on an overcoat and his homburg, tucking the covered envelope in the inside coat pocket. The church was a brisk eight-minute walk away. He’d be there, leave the envelope and be back home within twenty minutes.