HARCOURT had good reason to feel jubilant over the outcome of the Most trial and the recent passing of his Irish Arms Bill, which outlawed the possession of firearms and explosives and gave Irish authorities unrestricted powers of search and seizure. For the Scotland Yard detectives working to implement the Home Secretary's anti-Fenian strategy, however, the summer of 1881 proved an exceedingly difficult and frustrating period. In the words of one CID inspector, ‘[to] state that every possible resource at the disposal of the Criminal Investigation Department was taxed to its very utmost, [would be to put], even then, the matter very mildly indeed’, an impression confirmed by Vincent himself, who later recalled the ‘almost daily crop of false alarms and more or less circumstantial report of plots, all of which had to be sifted’.

Not all alarms proved false, however. On 10 April Robert Anderson received a missive from the American consul in Philadelphia, Captain Robert Clipperton, warning of intelligence received from ‘different secret sources’ which strongly suggested that bombings of ‘public buildings’ on Merseyside would be attempted shortly. Security at the Port of Liverpool was increased as a consequence, but all the same, in early May a gunpowder bomb rocked the Militia Barracks in Chester and in less than a fortnight, a similar device went off in the outer doorway of a police section house in Liverpool's Hatton Garden. Although neither explosion succeeded in inflicting injuries or serious damage to property, they managed to spread fear amongst the general public, cementing the notion that Rossa's skirmishers were out to do as much damage as possible on the British mainland.

On 10 June, less than a month after the Hatton Garden explosion, Liverpool became yet again the target of an attempted bombing, this time aimed at City Hall. It too failed to do any real harm if only because of the audacity of three local constables, one of whom dragged the bag holding the ‘infernal machine’ – a dynamite-charged, pipe-shaped device – into the middle of an adjacent street, where it exploded; and the incompetence of the bombers themselves, who, though armed, were easily apprehended and taken into custody following a short foot chase.