‘Go ahead and do whatever you need to do, never let it go,’ Barker says, seriously.

Lockhart looks at him and knows he is being trusted and says, ‘Thank you, sir.’

Barker rises from the desk. Before he can leave the office, Lockhart asks, ‘The boyfriend, gave evidence at the inquest, he was a doctor. Matthew Goodison, works at the hospital. Name mean anything, sir?’

Barker shakes his head. ‘Nope, nothing to me.’

*

Peterborough City Hospital is part of a huge out-of-town complex that includes sports grounds and factories. There’s always a queue of traffic going up to the main entrance, on account of all the people who have to get lifts or minicabs – I remember being stuck in it when I went there that day to see Dr Barnard, not long before I died.

Lockhart parks in the service car park round the side and walks up to the main atrium, vast and vaulted, with a round information desk. As he goes past the Costa franchise where I didn’t buy myself a coffee that day, he is filled with a sudden and overwhelming desire for a coconut flat white. Unlike me, he indulges the impulse. While he drinks it, he stands in front of the atrium wall and studies the A–Z Wayfinder – otherwise known as a map. The mortuary isn’t listed but he knows it’s at the back of the building. The Fracture and Orthopaedic Clinic is on the ground floor – it’s part of A & E. It’s 1.15 p.m. He’s a bit early for the mortuary; he’ll only be sitting around.

At Fracture Clinic Reception, he asks for Dr Goodison. The receptionist looks him up and down and says the doctor is with a patient but he might be able to pop out in a minute. ‘Tell him it’s not urgent,’ Lockhart says. You can’t really turn up in uniform at someone’s workplace and ask to see them without causing a bit of a stir.

He sits on one of the plastic chairs arranged along a wall in the waiting room. There is a smell of disinfectant and the parts of his trousers between the chair and the backs of his thighs become ever so slightly damp.

‘Officer?’

A tall young man with slick dark hair and a pale face has materialised in front of Lockhart. He must have moved quietly. He is standing quite close, looking down at him, with a greyeyed, assessing gaze. He is wearing a doctor’s coat.

‘Can I help you?’ Lockhart looks up and would stand at that point but hesitates because the doctor is so close to him, almost toe to toe, that if he levered himself upwards they would be nose to nose, which would feel oddly aggressive.

‘Are you the officer who asked for me?’ As if there were any other officers in the vicinity. The four patients ranged on other chairs are all staring at them.