‘Simply confirmation of timings and causes,’ he replied with the expression of a benign assassin. ‘In a case involving a prominent person, you’ll appreciate that police conduct will be under scrutiny and all procedures and avenues must be followed.’ Sara suspected that, for once, Pamela Bailly knew she’d overplayed her authority.

Patrick stood. ‘I drove in. Any south Londoners want a lift home?’ No replies. ‘Sara?’

‘If you’re sure.’

The second they closed the car doors and he’d started the engine, he pounced.

‘So what really happened to Morahan?’

‘God, Patrick, you’re not allowing much time.’

‘We may not have much time.’

‘OK. The appearance is that he died from auto-erotic asphyxiation.’

‘Except that you and I know he didn’t.’

She turned fiercely to him. ‘Actually, it just could be.’

‘No. It all smells wrong.’ He accelerated angrily. She watched him as he concentrated on driving.

‘Patrick?’

‘Yes.’

‘Are you OK?’

‘’Course I’m OK.’

‘It’s like you’re sitting on hot coals. It’s not like you.’

‘Aren’t we all?’

She didn’t answer, sure there was something else. Speeding through the empty streets of south London in the small hours, they reached the junction of Tooting Broadway with Webster Road.

‘Where’s your copy of the Blackburn files?’ he asked.

‘At my house.’

‘I’ll take them. We don’t have the original so we need to make a further copy. And put both copies in safe storage.’

‘I can’t do that.’

‘You’ve got to.’

‘Morahan gave them to me to keep.’

‘Sara,’ he said urgently, ‘if you get caught with those files – even being in possession of them, you’d be breaking the Official Secrets Act. That would be it. Operation over. And think what would have happened if Morahan hadn’t given them to you. It wouldn’t just be him dead – the evidence would have died with him.’

‘OK,’ she said weakly.

‘Another thing. When you were talking earlier, did Morahan finally tell you his source?’ Patrick asked. ‘’Cos knowing that puts you in danger too.’

‘No,’ she lied. Morahan, from the outset, had sworn her to secrecy about Sayyid. With the changed circumstances, she suspected she would have to tell Patrick soon enough – but not yet. It was certainly too early to tell him about the envelope behind the radiator – she had first to come to terms with it herself. But if they were both holding things back, she knew that either they must engineer a means of declaring their full hands together or their joint pursuit was over.

They drew up outside her home. The lights were on, Tariq still up. Patrick parked, switched off the engine and made no movement to get out. He turned to her and waited.

‘You’ve hardened since we drove down from Blackburn,’ she finally said. ‘And I don’t think it’s just Morahan.’