Mallon scratched his beard.

‘With all these London murders the newspapers will raise a racket. Any dead female has to be linked to this Jack the Ripper business in London. I had a query from Commissioner Harrel this morning.’

In the normal course, Swallow knew, the commissioner would only concern himself with ‘special’ crimes that had a political dimension. The security of the realm was paramount in the thinking of the Castle’s senior mandarins. It was G-Division’s primary task. An ‘ordinary’ murder, like that of Alice Flannery, would hardly merit attention. But Mallon was right: the so-called Ripper crimes were causing nerves to fray far from London’s East End.

‘You can tell him we’re pursuing every avenue, chief. Right now we don’t have a suspect, but we’ve just started on the investigation.’

Mallon nodded.

‘I know you’re “pursuing every avenue”. It’s at once a useful and a useless phrase. But I understand you’ve just started. And at least there isn’t anything political about it. Just keep me well informed.’

He paused, and indicated with his thumb towards the door through which Kelly and Waters had departed. ‘I told you I’d explain what those two wanted.’

Commonality of religion, background and career experience more often than not brought Mallon and Swallow to similar thinking without the need for discussion. He guessed that whatever the secret service men wanted, it had to do with politics.

‘I imagine they’ve got some plan afoot that’s likely to inflame passions, give us more work and yield no profit. And they think it’s a great idea,’ he said.

Mallon’s grin was without humour.

‘Precisely. They’re working flat out to cut the ground from under Parnell at the commission in London,’ he said. ‘They’re desperately looking for ways to blacken him.’

Swallow knew that as soon as the prime minister, Lord Salisbury, had announced the setting up of the inquiry to investigate the allegations that Parnell was encouraging the Fenians to violence, Smith Berry’s secret service unit had been further augmented by security detectives, including some drawn from the Special Irish Branch at New Scotland Yard. Some retired RIC men with security experience had been quietly drawn in too. Waters was one that he knew about. They kept to themselves, working out of private offices in the Upper Yard with a military guard outside, but most G-men had got to know some of them by sight. He had encountered them coming and going along Castle Street or Palace Street. They avoided the common police canteen behind Exchange Court that served both RIC men and DMP members. They drank separately too, avoiding the public houses around the Castle habituated by policemen.