Pat Finucane, who acted as solicitor for republican hunger striker, Bobby Sands, was shot dead at his north Belfast home in front of his wife and children. The De Silva report into the brutal murder of Pat Finucane, coupled with the prime minister’s searing confession to parliament, revealed probably the worst atrocity by the British state within UK jurisdiction in recent times.

Pat Finucane was a respected Belfast solicitor who had often represented republicans during the height of the Troubles in Northern Ireland. On 12 February 1989, he was assassinated while eating Sunday dinner at home in front of his wife, who was wounded, and their three children.

His murderers were loyalist gunmen, one of whom, Ken Barrett, eventually pleaded guilty when put on trial in September 2004. However, this was not just another of the many grisly loyalist killings at the time. Special branch agents were directly involved and, with IRA terrorism widespread, encouraged loyalist terrorists to kill republicans. So did the army’s secret Northern Ireland intelligence agency, the force research unit (FRU), a team of army officers tasked to recruit and train double agents within the paramilitary organisations.

Pat Finucane had republican sympathies but he was a solicitor, not an activist, still less an IRA member. Yet, as De Silva confirms, the FRU and other state security officers obstructed the subsequent police murder investigation which would have exposed their complicity.

The Finucane family fought bravely for many years to get the truth out into the open and wanted a public inquiry. The Labour government pledged to hold one as part of the peace process, however, the family would not accept one under the 2005 Inquiries Act, when Peter Hain was Secretary of State for Northern Ireland, the only vehicle available, because evidence from the security forces could be given confidentially. Their position was entirely understandable: why should they trust the British state that had killed Pat?

But the reason for this restriction was to enable the security forces to provide key evidence without compromising sources or methods and therefore their ability to continue confronting terrorism. The impasse remained until 2005, when the family apparently indicated they would accept an act inquiry.

Nevertheless, De Silva revealed that British government agents, supposedly acting in the name of democracy and the rule of law, totally betrayed those principles: a truly horrendous stain on Britain’s record in Northern Ireland. The prime minister should be held to his pledge that the attorney general will examine possible prosecutions and that other cabinet ministers will ensure that lessons are learned and nothing like this can ever happen again.