‘I want Bob flushed out,’ Swire said. ‘I want him dragged out from behind his firewall. I want him taken seriously. We’re becoming a laughing stock.’ She nodded sharply at me. Her hair did not move. ‘Especially after DC Wolfe’s recent stroll in the country.’

‘We have taken Bob seriously, ma’am,’ Mallory insisted.

She did not slap the table. She did not need to. She fixed Mallory with a look cold enough to give a snowman hypothermia.

‘Not seriously enough,’ she said. ‘The MP for Hillingdon North is highly thought of in Whitehall and Westminster.’ She inhaled deeply, exhaled slowly. ‘I am receiving phone calls.’

So that was it, I thought. The murders were too close to Ben King, and Swire had the full weight of Downing Street and Whitehall pressing on her back.

She turned to the older man on her right. ‘And this is Dr Joe Stephen of King’s College London. Introduce yourself, Dr Stephen?’

‘I’m a forensic psychologist and I’m here to give assistance in any way I can,’ Dr Stephen said. He had the smooth sing-song vowels of a Californian who had lived in London for twenty years. The Hollywood Hills meets Muswell Hill.

‘What can you tell us so far?’ Swire asked.

‘Well,’ he said. ‘Forensic psychology is more art than science. All I can do is look at the evidence, and estimate what kind of individual would commit these crimes.’ There was a file before him and he glanced down at it without, I sensed, really needing to. ‘To apprehend the unsub – sorry, the unknown subject – you need to understand that he is re-ordering the world. When women kill, they almost always kill someone they know. When men kill more than once, it’s almost always strangers. Serial killers are invariably male.’

Gane folded his arms. ‘So we’re looking for a man?’ he said. He smirked at Whitestone but she wouldn’t return his look, or his smile. ‘That narrows it down,’ he muttered.

Dr Stephen stared at him. ‘A white man,’ he added.

‘And why’s that?’ said the black DI.

‘Because the dead men are all white,’ Dr Stephen said, ‘and serial killers almost always kill within their own race. That’s not universal, but close enough to be considered a given.’

He looked a little rattled. He had come in wanting to be our friend and he was being forced to defend himself.

‘What kind of white man, Dr Stephen?’ Whitestone said, far friendlier than Gane. ‘Any guess as to age, motive, social group?’