THE strength of anti British feeling arising from episodes such as the deaths of the 10 hunger strikers in 1981 provided the IRA with large numbers of new members.
Dozens of sympathisers in Britain, including several from strong Irish nationalist backgrounds but with no previous IRA connection, offered to join the organisation.
The IRA accepted them with the view to their potential long term use as agents, known throughout the world of espionage and terrorism as "sleepers".
The men and women were simply left in place and told that one day they would be contacted to do some work.
Five years later, the first generation of the "sleepers" came to light during the IRA campaign which culminated in the bombing of the Conservative Party conference in Brighton in 1987.
Men, and a few women, who had not been heard of since their involvement in H Block demonstrations started reemerging in the company of IRA bomb teams sent over from Ireland with loads of explosives and guns.
The "sleeper" term belies the fact that their work includes the selection and reconnaissance of targets, as well as organising premises for preparing explosives and safe houses for the bomb teams.
A typical sleeper was Frank Ryan, from Harlow Essex who blew himself up while planting a bomb in St Albans in November, 1991. He had lived in England until aged 19 when he moved to Belfast, where he was trained and sent back to England.
At Ryan's funeral, a republican figure referred to "a generation of Ireland's youth who have acquired the skills to remain hidden, who come forward when required to do so", and asked: "How will the British defeat this invisible force?"
The IRA also infiltrates the annual exodus of school leavers taking up third level education places in Britain.
Barry O'Donnell, from Coalisland, Co Tyrone, was arrested in London in 1990 with two rifles. He was attending an agricultural college in Shropshire. He was acquitted in court but was later shot dead along with three other IRA men in Tyrone.
Felim O hAdhmail, caught with explosives in 1994 in Preston, had been attending the local polytechnic.
In the late 1980s, the sleeper recruitment extended to members of extreme left wing groups in Britain.
In 1993, two Englishmen associated with a group called Red Action were arrested after they were recorded on a video camera planting a bomb in a bin outside Harrods.
At least three of the long sentence IRA prisoners in Britain are mend with no significant Irish family connections who worked for the IRA.
Diarmuid O'Neill, the son of a first generation Irish family living in London, who was shot dead on Monday, morning during police raids which uncovered 10 tons of explosives was just another of the IRA's invisible force in Britain.
