James McArdle, 29, who was convicted for his "crucial role" in the massive explosion in February 1996 that killed two, injured dozens, and caused pounds 150m of damage in east London, is likely to benefit from the Good Friday peace agreement.
Official sources have indicated that people convicted since the agreement will probably have to spend no more than three years in jail.
Once the Northern Ireland (Sentences) Bill, currently going through Parliament, is passed, paramilitary prisoners held in the province will be eligible for release after two years.
McArdle, who has shown no remorse for his actions, would have to meet specific conditions, including undertaking not to support the IRA or carry out further acts of terrorism.
Unionist politicians were divided last night on the prospect of McArdle being freed in two years. Democratic Unionists, opposed to the peace deal, were outraged, but Ken Maginnis, security spokesman for the Ulster Unionists, who signed up to the agreement, said: "There is a bigger picture than James McArdle."
In what could be the last big IRA trial, McArdle, a bricklayer from Crossmaglen, Co Armagh, was convicted at Woolwich Crown Court, east London, on Wednesday of conspiring with others unknown to cause explosions.
But the judge yesterday discharged the jury from returning verdicts on charges that he murdered Inam Bashir and John Jeffries - the two newsagents who died in the blast - because of what John Bevan QC, prosecuting, described as a "clear and flagrant contempt" in the Sun newspaper. The two outstanding charges are to lay on the file and are unlikely ever to be retried.
The detonation of a lorry packed with a tonne of explosives, on the evening of 9 February was heralded by a series of "inaccurate and wholly inadequate warnings".
Mr Justice Kay, the trial judge, said he hoped the fact that McArdle was being sentenced at a time when the IRA campaign of terror could be coming to an end may offer a "crumb of comfort to those who suffered so much as a result of your actions".
He went on: "But nothing can realistically comfort the families of the two men who died and the many others who were injured and whose lives were marred by the dreadful explosion."
McArdle, although not very intelligent, was considered a competent, skilled, and trusted member of the bombing team to take the lorry packed with explosives from Northern Ireland to London.
On the trip the IRA unit stopped the transporter in which the bomb was hidden in River Road, Barking, East London, so that the bomb-maker could fit the timers and detonator before the final journey.
But the IRA's bomb was noticed while on the wasteland at River Road by another lorry driver, Arthur Ward. Two days after the bombing, police published a drawing of the lorry and Mr Ward telephoned the police.
Hidden inside the tyre the IRA team had dumped were tachographs which charted the vehicle's journey from Belfast via ferry to Stranraer, then to Carlisle and on to London.
There was also a magazine bearing McArdle's thumbprint.
Police also discovered two other thumb prints - one on an ashtray and another on a ferry ticket stub.
But McArdle - by now known to officers as the Triple Thumbprint Man - eluded police for 14 months until he was identified as the owner of the prints.