‘If she left,’ Kate asked Danny, ‘would they put her email account into the archive?’

‘Maybe email archive,’ he said.

He went in search of it. They were having more luck now. It turned out that the foreign secretary did have access to the email archive and Danny managed to find the contents of Petra Willis’s account: 9,212 emails had been sent and almost double that received. He searched ‘Jamaica’ and, with a few false starts, eventually found what they were looking for.

He opened James Ryan’s travel arrangements for his trip to Jamaica. There was a detailed account of his flights, combined with a schedule of meetings and functions covering every hour of daylight while he was there. At the end – after lunch with the Jamaican prime minister on the final day – the schedule merely referred to: at own arrangements. Depart at 1500 hours on flight JZ 216 from Norman Manley International, Kingston. Two days later it had the details of the inbound flight from the unspecified destination and the connecting BA flight back to London Heathrow.

The accompanying email, from Petra to James Ryan, said only: Have fun. But not too much! Xxx

Is there anywhere he goes that he doesn’t find someone to shag him?’ Danny asked.

‘What was that?’ Imogen yelled across.

‘Nothing,’ Kate replied. And then to Danny: ‘Apparently not.’

‘I don’t see what it tells us, though,’ Danny said. ‘I mean, he went off somewhere on a private plane while he was in Jamaica. So what? We knew that.’

‘Is there a way you can see if anyone has checked through this before us? If anyone else has accessed this exact part of the archive?’

‘Followed the same trail, you mean?’

Kate nodded.

‘Not unless I can log on as an administrator or hack in, which we’ve agreed is a bad idea, and even then … Well, I couldn’t guarantee it.’

Kate looked across at Imogen, still scrolling furiously through messages on her phone. She toyed with the idea of asking her if she would order the duty officer in Computer Support to hand over the administrator codes, then had a better idea. ‘Just try a search,’ she said. ‘Of names. Maybe someone just requested it. I mean, why go to the trouble of breaking in when you’re senior enough to demand something without any real questions being asked?’

Danny shrugged to indicate he got the logic of it. He tried Ian Granger first, but without any luck. But when he entered the name Alan Brabazon, a single email came up from Petra’s ‘sent’ folder: Dear Sir Alan, I hope this is what you are looking for. Do call again if I can do anything else, Petra.

Attached to it was the file containing the foreign secretary’s travel arrangements to Jamaica.

Kate studied the date. The email had been sent four months after the Jamaica trip had been completed.

Danny looked at her.

‘Christ,’ Kate said.

‘Is that what you were looking for?’ Danny asked.