It was not impossible that he might have managed to be back at Blackberry Lane at the time his sister was attacked, but he would have had to sprint or take a cab. Every driver who had been working that night was questioned. None remembered picking up a fare around Huband Bridge. Residents of the houses that fronted the canal between Portobello and Huband Bridge were visited. Nobody recalled seeing a running man.

Father Cavendish’s sick-call alibi was persuasive, if not watertight. But a second thundering letter to Commissioner Harrel from Archbishop Walsh ruled out further questioning of the young curate without first securing new evidence and clearing it through the commissioner’s office. The affront to one of God’s anointed would be raised in the Dublin City Council and at Westminster by Catholic representatives, Walsh threatened.

Swallow, Mossop and Feore re-interviewed the male employees of the New Vienna restaurant. Apart from Werner, the head chef, the sommelier and the professional waiters, they were either recent arrivals from the continent or casual workers doing menial jobs in the still-room or the wash-up. Those who knew Alice Flannery described her as quiet, private and keeping to herself. It seemed she had no friends among them, but no enemies either. None of them knew anything of her personal life. If she had a beau, or any relationship, they never heard it mentioned.

Meanwhile, Debbie Dunne, though small and slight, was proving herself strong and resilient. She made a slow but steady recovery from her injuries in the Dublin Infirmary at Jervis Street. Within a week she was well enough to be released. But she was required to attend every second day to have the dressings on her wounds changed. It was going to be a while before she would be well enough to get back to work selling fish.

Swallow and Pat Mossop questioned her after her discharge from hospital.

‘Any detail at all that you can remember, anything that’s come back to your mind since, might be a help,’ Mossop told her in the bare room where she lived with her younger sister at Ringsend.

‘Jesus . . . didn’t I tell the other bobbies . . . everythin’ I remember,’ she groaned through split lips. ‘I was fightin’ for me life and the few shillin’s I’d earned in the day.’

Her face was still a mass of bruising, yellow and blue. Her left arm was encased in plaster, the ulna having been badly fractured. It would be months before she would have the strength again to push a barrow. Swallow felt something between anger at what had happened to the girl and admiration for her grit.

‘You said he had a smell. You told the other detectives it was a “musty” smell,’ Swallow said gently. ‘Would you say it was smell like a horse, or a dog, or what?’