Gillard and Shireen exchanged frustrated glances. Arrowsmith’s account was entirely plausible, and it would take much more work from the SFO’s forensic accounting team to prove that it wasn’t true. Gillard decided to return to firmer ground.

‘Do you know where Ray Slater currently is?’ Gillard asked.

‘I have no idea, why should I? He reports to Shane Devlin.’

Gillard was careful with how he phrased the question ‘We urgently need to speak to him in relation to the death of Ozzy Blanchard.’

Arrowsmith rearranged his face into an expression of utter perplexity: ‘Detective chief inspector, are you seriously thinking that a professional private detective would be involved? Surely it’s the Ticketts who did this?’

‘The entire Tickett family were in custody at the time of the killing.’ Gillard leaned forward and steepled his fingers. ‘We have Slater, on tape, admitting he was paid a hundred grand for the hit. We think you paid him.’

‘You’re being absurd.’

Gillard opened a manila file in front of him, and slid forward a photograph culled from the Chieveley CCTV. ‘Do you recognise this man?’ The picture was of a thickset fellow wearing sunglasses, a face mask and a stained hi-vis jacket.

‘No.’ Arrowsmith pushed the photograph back across the desk.

‘It’s Ray Slater, incognito. This image was captured at Chieveley Services at around the time that Blanchard was killed. On your orders.’

‘This is utter nonsense. I’m as shocked as everyone else that Ozzy was killed.’

‘Sure you are. There is a phone call from your landline to Slater’s phone just a couple of hours earlier.’

‘What day are we talking about here?’

‘The day you were released from hospital. You rang home, and a few minutes later someone from your home, almost certainly Francesca, rang Slater. Presumably to tell him to go ahead with the plan you had previously discussed.’

Arrowsmith shrugged. ‘You have a lucid imagination, but not a shred of evidence.’

Shireen leaned forward. ‘Mr Arrowsmith, we are taking apart your finances. You paid Ray Slater to kill Blanchard, and we will find out how. There’s always an audit trail.’

‘Look, I liked Ozzy Blanchard. He was reliable, hard-working and spent many hours more than he could have got away with on his work. That was how he fooled me for such a long time.’

Arrowsmith had clung tenaciously to his story. Gillard knew that the admission by Slater, made in a phone call with Hoskins, might be inadmissible in context of the entrapment. They really needed hard financial proof, and Arrowsmith rightly guessed they didn’t have it. If they did, why press him so hard for an admission? Seeing as they could make no further progress, Gillard terminated the interview and the prisoner was returned, still bitterly complaining, to his cell.

‘How long will it take to get every scrap of his financial records?’ Gillard asked Shireen.