Late on the Friday evening, one of those formless, fallow days that run between Christmas and New Year, Swallow made his way through the gloom from Exchange Court to the ABC telegraph office in the Lower Yard. Had he not done so, he later reflected, had he sent a clerk to discharge a routine task, it was likely that he would never have known about the telegram from Berlin.

Earlier he had recounted his conversation with Charlie Vanucchi to Mallon.

‘You gave him a week?’ Mallon was incredulous.

‘Yes, chief. I’d say he genuinely knows nothing. So I think he needs the time.’

‘Sounds as if you’re going a bit soft, Swallow,’ Mallon said.

Swallow could not be sure how seriously the quip was intended to be taken.

Mossop wanted to make good on his promise to young Debbie Dunne that her fishmonger’s stand would be protected from predators until she was strong enough to go back to her trade at Misery Hill and Cardiff Lane. Would-be usurpers were to be threatened with prosecution for failure to hold or display street-trading licences unless they allowed her young sister to do business in her place.

‘You’d be best advised to have the divisions put out warnings first,’ Mallon had counselled. ‘If you start issuing summonses without notice there’ll be a lot of stink. The beat men will start getting hell from the fish-ladies and God knows what might happen.’

‘The plan would be that there wouldn’t be any summonses, chief,’ Mossop explained. ‘It’s just a threat. Sure, if we locked up a fraction of the unlicensed street traders in the city there’d be standing room only in Mountjoy and Kilmainham.’

‘Even so,’ Mallon countered, ‘do it by the book. Get a notice out on the routes and let the beat men start issuing the warnings. That way nobody can say we’re not playing fair.’

And so it was that on Friday afternoon Swallow spent an hour drafting an instruction in Mallon’s name for distribution to all stations on the ABC. It would be included in the daily and nightly charges delivered by the shift sergeants before their sections went out on their beats. All street traders were to be cautioned that their licences needed to be in order and that there would be consequences for any who did not comply with the law’s requirements.

He stepped into the telegraph office a few minutes after six o’clock. Reports from all thirty-five police stations across the city were transmitted promptly on the hour, so the room was filled with the chattering noise of printer machines, spewing out details of petty crime, property both stolen and recovered, missing animals and snatches of what was supposed to be criminal intelligence: a known housebreaker seen in a suburban street and a pickpocket spotted boarding a tram that would take him to Sackville Street to ply his trade.