These two cases arose from two attacks in late 1974, in which seven people died. In the first, in October, a bomb left under a bench in a Guildford pub killed a civilian and four soldiers, two of them women.
A month later a soldier and a barman died in a bar in Woolwich when a bomb, made of 6lb of gelignite packed with bolts, was thrown through a window.
The authorities responded by heightening security, bringing in tough new laws, and prosecuting several dozen people. While some of those imprisoned were members of the IRA, others are now seen as victims of miscarriages of justice. The general verdict on the official response to the mid- 1970s IRA threat was that the correct balance between security and civil liberties was not struck and that injustices resulted.
These consigned uninvolved people to prison for lengthy periods, and eventually dealt a traumatic blow to the credibility of the criminal justice system.
In Ireland there was much debate on whether those in authority knew the wrong people were being convicted, cynically going along with it in order to protect the system and deny the IRA a propaganda victory. The most serious allegations were encapsulated by a campaigning Irish nun, Sister Sara Clarke. She wrote that those convicted were "victims of anti-Irish racism, public and press hysteria, police brutality, frame-ups and biased courts."
An alternative explanation is that police in Britain, unlike those in Northern Ireland, were unused to coping with the IRA. It has also been argued that juries in Britain proved much more ready to convict in terrorist trials.
Of the 127 people killed in Britain over the course of the Troubles, 56 - almost half - died in 1974 and 1975 as the IRA went on a sustained offensive in London and the Midlands.
Pub bombings in Birmingham claimed 21 lives in December 1975, while the IRA's notorious "Balcombe Street gang" killed at least 16 people and carried out up to 50 bombings and shootings in the London area.
The net effect was a build-up of public and political pressure to catch the bombers. For the authorities the breakthrough came in December 1975 when four gang members were cornered after shooting at a Mayfair restaurant.
In 1977 they were sentenced to 47 terms of life imprisonment, but caused a stir when one of them said from the dock that they had also carried out the Guildford bombing. They had not been charged with this, and others had already been jailed for it.
Some accuse the authorities of concealing the fact, which emerged later, that forensic evidence in the Guildford bombing was similar to that in other attacks known to have been carried out by the Balcombe Street gang.
The Guildford and Maguire cases gave rise to unease in some circles as early as the 1970s, not least because those convicted made such unlikely terrorists. For example, three weeks after the Guildford bombing one of the four, Carole Richardson, was assaulted in the street in Folkestone.
Her reaction - incredibly for an alleged member of the IRA - was to call the police and drive round the streets in a squad car, looking for the man who had attacked her.
One of the Maguire Seven belonged to a Conservative club and had a bust of Winston Churchill in his house. Another was applying to join the Metropolitan Police when he was arrested.
In addition, contradictions in the often jumbled alleged confessions made by the accused were presented by the prosecution as part of a sophisticated technique of counter-interrogation designed to confuse and mislead police.
In 1989, however, the Guildford case was referred back to the Court of Appeal after a fresh police investigation. Later that year the court quashed the sentences, Lord Lane saying of some police evidence: "The officers must have lied."
In 1991 the Court of Appeal overturned the sentences on the Maguire Seven, all of whom had by then completed their sentences.
In the end the saga had many casualties. In the first instance there were the many people killed by the IRA, then there were the dislocated lives of those who spent many years in prison.
Finally there was the justice system itself, which was seen to function badly and then to display reluctance to admit mistakes.
The Guildford and Maguire cases may now come to be regarded as closed, but others involved in justice miscarriages may now press their case. Hugh Callaghan, one of six men jailed for the Birmingham bombs but later cleared, last night said they too would welcome an apology.
MISCARRIAGES OF JUSTICE
Six Irish Catholic men were wrongly convicted in 1975 of the murder of 21 people after bombs exploded in the Mulberry Bush bar in Birmingham in November 1974. They were released on 14 March 1991 when their convictions were quashed by the Court of Appeal. Scientific evidence was shown to be flawed.
Judith Ward was wrongly convicted in 1974 for bombing an Army coach on the M62 motorway two years earlier. Twelve people died in the explosion. Ms Ward served 17 years in prison. Her conviction was quashed in 1992.
In 1976 Annie Maguire, five members of her family, and a family friend were imprisoned in London for possessing explosives. All seven of the convictions were overturned in 1991.Reuse content