Simon counted them off on his fingers. ‘One, he didn’t need the car if he was heading into town—no one drives into central London. We know Seed doesn’t—I saw proof of that on Monday night. Check CCTV footage between Ruskington Road and Highgate underground—he’ll have gone for the tube within half an hour of killing Gemma Crowther, or jumped on a bus on Muswell Hill Road.’

‘Simon,’ Charlie muttered, ‘you don’t know that.’

‘Two, I agree the car’s evidence of his presence at the scene, which could mean one of two things. Either he’s hoping you’ll have him down as missing, possibly also dead, as likely to be another of the killer’s victims as to be the killer himself . . .’

‘Bit of a stretch, isn’t it?’ Milward frowned.

‘I’m keener on the second possibility: he knew that as soon as Gemma Crowther turned up murdered, he’d be high up on the list of suspects whether you found his car or not.’

Dunning rubbed his nose. Milward looked perky again—a contented piglet.

‘I’m right, aren’t I?’ said Simon. ‘There’s a link between Aidan Seed and Gemma Crowther. Which you wouldn’t have found as quickly as you did if I hadn’t given you Seed’s name.’

Silence from the other side of the table.

‘That’s okay,’ he said. ‘You’re welcome. How long are you going to wait before searching Seed’s car? Or have you impounded it already?’

‘Let’s not waste words,’ said Milward. ‘You know I can’t tell you anything. I’m interested to hear your thoughts, though.’

Simon had plenty. ‘If there’s a link between Seed and Crowther, is it one that supplies Seed with a motive for murder?’

Milward ran her tongue over her lower lip before saying carefully, ‘Let’s suppose, hypothetically, that it were.’

‘Crowther can’t have known,’ said Simon. ‘She knew him as Len Smith, she invited him back to her house. She didn’t know about whatever it was that linked them and gave him a reason to want her dead. Her boyfriend didn’t know either—only Seed knew.’

‘Cloud-cuckoo-land,’ said Dunning impatiently, turning the Vegas croupier eyes on Simon, eyes that had seen it all before: the worst humanity had to offer. ‘Either Gemma knew Aidan Seed or she didn’t. If she knew him, not much point in him changing his name to fool her. If she didn’t know him, why bother?’

‘You can do better than that,’ said Simon. ‘Or maybe you can’t. It’s possible to know a name but not the face that goes with it.’