CTC – also known as SO15 – is Counter Terrorism Command, a special operations branch in the Met. They have over a thousand surveillance officers at their call. Before I came to 27 Savile Row, I had been one of them.

I looked at Whitestone to see that I had made the right move. But she was still staring at the screen.

Edie Wren and Billy Greene went out of the door just as up on the big screen the noose was placed around the young man’s head.

‘Do you know why you have been brought to this place of execution?’

He did not reply.

He blinked back tears and I saw the track marks of the long-term heroin addict on his arms.

‘I wonder who he killed?’ Whitestone said, her voice small and far away, as if she was talking to herself.

‘It appears to be live,’ Colin Cho said. ‘Thank you all for your patience.’

There were photographs on the white-brick walls that had been stained green by time.

Two photographs.

A smiling soldier, in black and white, a British soldier of the war against Nazi Germany.

And a colour photograph of the same man, some sixty years later, an old man now, leaning back in an armchair and grinning with a modest Christmas tree behind him.

‘According to the online community,’ Colin Cho said, ‘the old gentleman is Bert Page, a Normandy veteran and a retired Fleet Street printer, who is still in a coma after being mugged by Darren Donovan, a heroin addict.’ A pause. ‘And Metcall has received numerous confirmations that the young man in these images is Darren Donovan . . .’

‘So – if that’s true – they’re not just hanging murderers now,’ Dr Joe said.

‘And it was never only murderers that were hanged at Tyburn,’ Professor Hitchens said. ‘In the eighteenth century there were two hundred offences punishable with death in this country. Vagrancy. Theft. Sacrilege. Being in the company of gypsies for one month . . . They hanged seven-year-old children who stole a letter, and they hanged highwaymen, and they hanged the men who executed Charles I.’

‘I want these identities confirmed,’ I said. ‘The old man in the photos and the young man they’re hanging. I’m not taking the word of the online mob.’ But, deep in my bones, I already believed it. Darren Donovan, a drug addict, had attacked and robbed an elderly man for a few coins. And now he was going to pay for his crime. With his life.

‘Do you know why you have been brought to this place of execution?’

This was the most leisurely hanging.

Darren Donovan did not plead for mercy as Mahmud Irani had pleaded for mercy.

Darren Donovan did not fight for his life as Hector Welles had fought for his life.