Charles didn’t want to discuss Timber Wolf. ‘Let’s just wait and see. There may be no news to break. He may surprise us all by turning up tonight.’

He next summoned Alex, director of security overall. Alex was Eric’s boss and, like Eric, was due to retire. He was a cheerful Scot with a ruddy farmer’s face. Nothing seemed to surprise him and he sustained his good cheer despite a daily diet of problems. ‘There’s something you need to know, Alex, which no one else needs to know. In fact, it’s very necessary that no one should know.’ He indoctrinated him into the Timber Wolf case and told him everything about Gareth, except the plan to continue the case himself.

‘So he’s just disappeared, vanished completely? No note, no message, no communication at all? Sure he hasn’t gone under a bus? Worth checking with police and hospitals. It happens all the time.’

‘Of course, we’ll have to do all that but you might have expected Suzanne to have heard something by now if that had been the case. Our priority, apart from finding him, is to establish whether he’s blown the Timber Wolf case or any of the many other cases he knows, whether he’s involved with anything more serious than the expenses fiddle we now know about and to get MI5 to agree to open an investigation, which will mean suspending him to start with.’

‘HR will say that employment law says you can’t suspend anyone without telling them and giving them reasons. And in this case there’s no one to tell.’

‘But you can withdraw his vetting clearance and cancel his pass, can’t you? No one’s allowed to work here without vetting or allowed in the building without a valid pass. As soon as you do that he’s effectively suspended. On full pay. We’ll go on paying him while he’s investigated as a security risk. It buys us time for MI5 to do a proper job, assuming we haven’t found out what he’s up to in the meantime.’

‘I’ll set the wheels in motion.’

Charles knew what it was like when the power of the state turned against you, ineluctable and as impersonal as the sea. Within minutes Gareth would be transformed from insider to outsider, from being an enabler of state power to the object of it, a case for investigation. Conceivably, he could be exonerated and unexpectedly rewarded, as Charles had been; more likely, he would be subjected to due process and afterwards neither victimised nor further punished, merely excluded. And for those who aspired to do the state some service, exclusion was the deepest and most lasting punishment.