The interview rooms at AB are featureless cubes with Windsor blue walls and scuffed wooden trim. There was a scarred wooden table, chairs, the standard double tape recorder and a CCTV camera enclosed in an opaque Perspex bubble that hung from the ceiling. In the hour or so since he’d been placed in it, Zach had managed to create a pile of chocolate bar wrappers and shredded polystyrene cup.

‘Hello gorgeous,’ he said as me and Lesley entered.

‘I didn’t know you cared,’ I said.

‘Got anything to eat?’ he asked. ‘I’m bare hungry.’

I swept the rubbish into the bin and slapped down a suspiciously floppy package wrapped in the greaseproof paper in front of him. Zach opened it cautiously, took a sniff and then gave me a broad smile.

‘From Molly?’ he asked.

‘What is it?’ asked Lesley.

‘Brawn sarnie,’ he said.

‘Okay,’ said Lesley, who as a proper Essex girl knew her lights from her livers. She’d once spent a happy half an hour explaining what strange and secret bits of the animal’s body regularly turned up in Molly’s ‘traditional’ cooking. If you don’t know already I’m not going to tell you what brawn is. Let’s just say that the common name for it is head cheese and leave it at that.

If she hadn’t been wearing a mask, I’m pretty certain that even Lesley would have looked shocked at the enthusiastic way Zach tucked in.

There’s several schools of thought about using tricks and treats in an interview. Seawoll says that in the old days, when just about everyone smoked, if you withheld the fags for long enough your suspect would tell you just about anything in return for a puff. Which was fine, if all you wanted was a result. But if you were looking for accurate information you needed to be a bit trickier.

In our pre-interview discussion the consensus was that the problem with Zach was not going to be making him talk, but getting him to talk sense. We didn’t think low blood sugar would be helpful but, as Stephanopoulos pointed out, we didn’t want him hyper either – hence the offal sandwich.

‘Let’s talk about your friend,’ I said.

‘I’ve got a lot of friends,’ said Zach.

‘Let’s talk about the one that’s good with his hands,’ I said.

Zach gave me a blank look but he wasn’t fooling me.

‘Pale face,’ I said. ‘Hoodie, digs out concrete with his bare hands.’

Zach glanced at where the twin cassette tapes whirred in the recorder.

‘Are you allowed to talk about this stuff?’ he asked.

‘It’s just us here,’ said Lesley.

If only, I thought. There being a good chance that Nightingale, Seawoll and Stephanopoulos were watching on the monitor and maintaining a blow-by-blow commentary complete with score cards.