I stepped into the lift. ‘You’ll just have to try to be strong,’ I said, thinking that they should teach mindless banter at Hendon, the Training School of the Metropolitan Police.

The gangly figure of PC Billy Greene was waiting outside the Intensive Care Unit. He looked half asleep but snapped to attention when he saw me coming.

‘Back on the beat,’ I said.

He grinned. ‘Yes, DC Wolfe.’

‘Visitors?’

‘The same gentleman,’ Greene said. ‘His friend. The politician. Mr King. It’s still restricted visitors but Mr King must have had a word.’

The door to the ICU opened and a doctor emerged.

‘Doctor,’ I said, ‘DC Wolfe. When can I talk to your patient?’

‘Detective,’ he said. ‘Mr Philips has a severe tracheal rupture. Someone, as you know, stuck a knife through his windpipe. Thirty per cent of patients with tracheal tears die, most of them within one hour.’

‘I get it,’ I said. ‘I understand the severity of the injury.’

‘I’m not convinced you do. Mr Philips is currently sedated and breathing through a ventilator. If he survives, he will need extensive surgery to repair the severed windpipe. If he has surgery, even surgery that is successful, he will have breathing difficulties for the rest of his life, due to a narrowing of the airways in his throat.’ He looked up from his notes. ‘And you’re seriously asking me when you can talk to him?’

‘Because we believe he may have seen his assailant’s face,’ I said. ‘He wouldn’t have to speak. He could write something down.’

The doctor looked at me with open hostility. ‘He’s not well enough for visitors,’ he said. ‘And I’ll let you know when you can talk to him.’

He walked off.

I gave Greene my card.

‘If he wakes, you call me. If his condition changes, you call me. And if there are any problems, what do you do?’

‘I call you.’

‘Good.’

Then I entered the Intensive Care Unit. PC Greene followed me inside, concern flitting across his face as he watched me scrub my hands in one of those big deep sinks you only find in ICUs.

‘Don’t worry,’ I said, ‘I’m not going to operate on him. And I’ll be quick.’

I went inside Philips’ room. In the gloom I could see a figure propped up in bed. I could not recognise him as the man I had last seen emerging from the woods at Potter’s Field with blood pouring through hands around his neck. Guy Philips looked like the sole survivor of some catastrophic disaster. He looked like someone I had never met.