[3] Born into a staunchly Irish republican, Roman Catholic family in Belfast, McGartland grew up in a council house in Moyard, Ballymurphy at the foot of the Black Mountain.
He recounted in his book Fifty Dead Men Walking that he occasionally drove IRA punishment squads around and overheard them boast about the beatings they had meted out to their victims.
Davy Adams immediately gave McGartland his first assignment, which was to check the house of a well-known Ulster Volunteer Force (UVF) figure.
[14] He convinced his IRA associates that he was a committed member of the organisation and he successfully led a double life, which was kept secret even from the mother of his two sons.
During his time as a Special Branch intelligence agent, he became close to senior IRA members, having daily contact with those responsible for organizing and perpetrating the shooting attacks and bombings throughout Northern Ireland.
[18] Although McGartland says he prevented the IRA from carrying out many "spectaculars", including the planned bombing of two lorries transporting British soldiers from Stranraer to Larne that could have resulted in the loss of over a dozen lives,[19] his reported greatest regret was his failure in June 1991 to save the life of 21-year-old Private Tony Harrison.
[20] A taxi driver and republican sympathizer, Noel Thompson, who picked Harrison up at Belfast airport and informed the IRA was later jailed for 12 years for conspiracy to murder.
[21] In that same year 1991, McGartland provided information about a mass shooting attack planned on Charlie Heggarty's pub in Bangor, County Down, patronised by British soldiers after a general football match between the prison wardens.
[22] McGartland wrote that diaries of the late Detective Superintendent Ian Phoenix, head of the Northern Ireland Police Counter-Surveillance Unit, showed that he and other Special Branch officers had advised senior RUC officers against stopping the gun couriers' vehicles, as doing so would put McGartland's life at risk and allow the actual IRA gunmen to escape.
With his cover blown, McGartland was kidnapped in August 1991 by Jim "Boot" McCarthy and Paul "Chico" Hamilton, two IRA men with previous convictions for paramilitary activities.
He later alleged that McCarthy and Hamilton were also RUC informers based on what he had personally observed of the men during his kidnapping as he waited to be interrogated, tortured and subsequently executed.
[25] McGartland moved to the northeast coast of England, receiving nearly £100,000 (£261,400 today) to buy a house and establish a new life in Whitley Bay, Tyne & Wear, going by the name Martin Ashe.
[28] In 1997, his identity was revealed publicly by the Northumbria Police in court when he was caught breaking the speed limit and subsequently prosecuted for holding driving licences in different names, which he explained was a means of avoiding IRA detection.
[31] In 1999, he was shot six times at his Whitley Bay home by two men, receiving serious wounds in the chest, stomach, side, upper leg and hand.
"[35] The day after McGartland was shot, the incident, along with the murders of Eamon Collins, Brendan Fegan, and Paul Downey, was cited by Ulster Unionist leader David Trimble in an interview with reporters in Belfast, to question whether the IRA ceasefire was being maintained.
He reminded Mo Mowlam, Secretary of State for Northern Ireland, that this was a condition of the early release of paramilitaries under the Good Friday Agreement.
[39] McGartland criticized the police for inadequate protection, but offered to testify on their behalf, saying: "There are people who have been the victims of terrorist attacks, who've lost loved ones, and some of them haven't been compensated.
[12] McGartland has said that his relatives have received harassment from Republicans;[12] in 1996, his brother Joe was subjected to a severe and prolonged IRA punishment beating with baseball bats, iron bars and a wooden plank embedded with nails.
After highlighting the two books he has written about his life as an undercover agent, one of which was made into a successful film, he also noted there have been six television documentaries on him and a number of newspaper articles.
"[44] May's department the Home Office oversees MI5 and she herself had signed the application in a court case brought by McGartland and his partner, both of whom are obliged to live under secret identities that were provided by MI5.
McGartland additionally has a contract which was signed by MI5 after he was shot in England in which the representatives of the PSNI and Northumbria Police acknowledged his service in general terms.
Because he is unable to claim State benefits due to security reasons MI5 had previously helped him financially; however this assistance was withdrawn after he gave an interview to the Belfast Telegraph.