[2] At the same time separate non-paramilitary forces were set up in the largest cities: Dublin, Belfast, and Derry.

Although the police were involved in "frequent collisions" with union members and used tactics such as baton charges against them, a vice-regal commission cleared them of wrongdoing after the events – though their reputation had suffered considerably.

[3] One of their number David Neligan (who was an IRA agent) records in his book "The Spy in the Castle" that the majority of the DMP uniformed personnel observed a neutral role, restricted to traditional policing functions.

The political "G" Division did not come off so lightly, and selected "G men" were first given warnings by the Irish Republican Army in April 1919.

Several DMP officers actively assisted the IRA, most notably[5] Edward Broy, who passed valuable intelligence to Michael Collins throughout the conflict.

His fate in the film is based on that of Dick McKee, who, with Peadar Clancy and the civilian Conor Clune, was murdered after torture in Dublin Castle on "Bloody Sunday", 21 November 1920.

[6] After the creation of the Irish Free State, the DMP became known as "Políní Átha Cliath" (Police of Dublin) from 1922 to 1925, after which the force ceased to exist as a separate entity, being absorbed into the Garda Síochána (Guardians of the Peace).