As soon as they pulled up on the forecourt, a manservant came out to hold the bridle while they got out of the trap. When the visitors walked towards the house, Hooper stayed half a pace behind Peter. The butler was waiting at the open door, face darkened by grief.

‘This is a house in mourning,’ he said, solemnly. ‘As a result, this is not a fit time to welcome stray visitors.’

‘We are not stray visitors,’ said Peter with polite firmness.

He was about to explain why they were there when he saw, over the butler’s shoulder, a tall, slim figure entering the hall at the far end and coming towards them. Peter guessed at once that it must be David Mellanby, the younger son. When he saw what the man was wearing, he realised that Hooper had failed to provide a telling detail about him. David Mellanby was a clergyman.

Micah Yeomans and Alfred Hale were back at their usual table in the Peacock Inn that morning. When one of their colleagues came in, they looked up with interest.

‘Well?’ asked Yeomans. ‘Do you have a name?’

‘Yes and no,’ said the other.

‘Talk sense, man.’

‘Yes, I have a name. In fact, I have more than one. But, no, I don’t think that any of them is the name you want.’

‘Let us be the judge of that, Chevy,’ said Hale. ‘What have you discovered?’

Chevy Ruddock cleared his throat. He was a big, ungainly man in his twenties who took great pride in his work with the Runners. Tireless and ever-willing, he’d been rounding up some of the many paid informers on whom they relied to betray their criminal associates. Beads of sweat ran down Ruddock’s face. He’d clearly exerted himself.

‘Come on,’ prompted Yeomans. ‘Who was the assassin?’

‘Two people gave me the same name,’ said Ruddock.

‘What was it?’

‘Ezra Gammon.’

Hale snorted. ‘That’s impossible.’

‘Next time you see these two barefaced liars,’ said Yeomans, rancorously, ‘kick their arses from one end of Piccadilly to the other.’

‘Why is that?’ asked Ruddock.

‘Ezra Gammon is somewhere in the middle of the Pacific Ocean on his way to Australia. I know that because I had the pleasure of arresting him. You’ve obviously forgotten that the rogue was transported. Since he’s lying in chains below deck, how could he possibly shoot someone dead in Covent Garden?’

‘Ah,’ said Ruddock. ‘I had a feeling they were misleading me.’

‘Then you should have knocked their heads together.’

‘Yes, sir.’

‘Gammon aside, what other villains were suggested?’

Ruddock took a notebook from his pocket and opened it to the appropriate page. He read out four names in succession, each one producing derisive sneers from the others. Yeomans grabbed the notebook from him and tore out the page from which Ruddock had been reading. He thrust the notebook back into the younger man’s hands.

‘Those names are worthless,’ he snarled.