Tom went back inside to find Garvey. An admiral was now bending her ear.

‘Excuse me. Good evening, ma’am. I’m Tom Buckingham.’

She peered at him. ‘Do I know you?’

‘Not exactly. I work for Stephen Mandler.’

The admiral looked particularly perturbed at the interruption. Tom ignored him, keeping his focus on Garvey. ‘Do you know a Sahim Kovacevic? Do you know if he’s here? I need to talk to him.’

Garvey’s frown deepened. ‘Oh you do, do you.’

‘You know if he’s here?’ Tom repeated the name. ‘This is important.’

The admiral stepped between them. ‘Look here, I don’t know who you are but the home secretary does not want to be interrupted.’

Something about the directness of Tom’s look and tone must have made her realize that he wasn’t wasting her time. ‘He’s with a pretty girl in a blue dress. Should I be concerned?’

‘Not for the moment. Thanks.’

He snaked back into the crowd and wove his way through the guests, searching for a blue dress. The throng was getting thicker as the minutes ticked down to the President’s appearance.

The woman in the blue dress – the one he had seen in the queue – was about fifteen feet away, with a young man, black hair, who could have been from Bosnia or Blackpool or a hundred other places. They weren’t with anyone else. Tom’s phone buzzed: a photo from Woolf of Sahim in a TV studio. Definitely the same guy. When Tom looked up again, the woman was alone.

Tom stepped left, then right, and got eyes on him moving off to the left and away from the main crowd. Tom followed. Sahim went out into a wide carpeted hallway with fancy Regency-type lampshades on the walls. He seemed to be heading for the Gents. Ahead of him was a security guy, easily identified by his shoulder epaulettes, carrying a white cardboard box gift-wrapped with red ribbon. He went through the door to the cloakroom and Sahim followed.

Tom waited outside. He wasn’t going to let Sahim see his face. There might come a stage when he had to get up close to him. But for now there was no need: he knew where he was; he wasn’t going anywhere. Tom carried on to the other side of the door, where there was a row of chairs. Before he got there, the security guy came out again, but he was no longer carrying the box.

Tom was committed to passing him. The security guy was walking with purpose, and as soon as he’d disappeared, Tom went straight to the door and stepped inside. He was confronted by a bank of four cubicles, all with beautifully varnished, full-height wooden doors.

The door at the far end was engaged, so he stood at a basin, ready to wash his hands if someone came in.