‘Even better, he had a legitimate set of keys,’ said Stephanopoulos. ‘And this property has had the same owner for five years.’

‘Let me guess,’ I said. ‘Our old friend Mr Shell Company.’

‘Oh, yes,’ said Stephanopoulos. ‘Which is a close relative to A.N. Other Shell Company and a Guernsey registered investment house who bought it on behalf of one James Hodgkins, a.k.a. Martin Chorley.’

I looked across the street to what I’d been assured was Tyburn’s bedroom – obscured now by the blue sheeting the forensic people had rigged to cover the shattered window. Less than thirty metres I thought – a good sniper would barely need a telescopic sight.

The gun had been whisked away even before the body. An L96A1 firing a standard 7.62 mm NATO round. It was the standard British sniper rifle as used by the Army, the Navy and the Met’s own SCO19. Probably, Stephanopoulos said, one of those guns that occasionally fall off the back of a military supply lorry. A bit specialist for your basic London underworld, who tended to favour cheaper and more personal forms of assassination – although if I’d been planning to take a shot at Lady Ty myself I’d have probably opted for a drone strike from a nice air conditioned Air Force base in Arizona.

And even then I’d do it under an assumed name.

He’d got off only the one shot before he died. It was a bolt action weapon, but still I would have thought he’d have had time to take a second one – just to be on the safe side.

Three hours later they still hadn’t found the bullet he’d fired.

‘What killed him?’ I asked.

‘Single stab wound to the chest with a heavy double edged blade,’ said Stephanopoulos. ‘Through his heart and out the other side.’

‘What, through the ribs?’

‘Sheared right through two at the front and one at the back,’ she said. ‘Clean cut.’

‘A sword,’ I said.

‘That’s what they think, but they haven’t finished the PM yet.’

If I had to guess I’d have said a classic fourteenth century English arming sword like the one I’d once seen worn by a young man in a hallucination I’d had when I was busy suffocating under the eastbound Central Line platform. A young man who styled himself Sir William Tyburn, who had been god of the river from back when it was a wild stream rushing down to Father Thames.

For obvious reasons I kept this intriguing observation to myself.

‘Chorley’s had this place for five years,’ said Stephanopoulos. ‘Never had any tenants in here in all that time.’