They were two self-proclaimed British government spies who achieved notoriety on both sides of the Irish Sea.
Brothers Kenneth and Keith Littlejohn were jailed for 20 and 15 years in 1973 for a £67,000 bank robbery in Dublin.
Both brothers complained they should never have been extradited because their offence was a political one.
A year after their incarceration, the brothers caused huge embarrassment after they escaped from Mountjoy jail in March 1974.
Keith was recaptured almost immediately but his brother was not recaptured until August 1975.
They languished in Mountjoy's notorious 'B' basement where they were housed to protect them from attacks by other prisoners and for "security reasons".
In his handwritten letter to Mr Haughey, contained among the state papers, Keith Littlejohn said: "I am certain no person has been required to endure such an ordeal in any prison in western Europe in this century."
Pleading for a release date, he told the Taoiseach that, while they were imprisoned as criminals, they had been informed that their release would be a political decision.
Both were released in 1981.