The law firm is instructed by Ann McKearnan, the sister of Gerry Conlon, one of the Guildford Four who were wrongfully imprisoned for the 1974 Guildford pub bombings. Mr Conlon died in 2014.

KRW is also assisting a young soldier who survived the bombing of The Horse and Groom pub, which killed four soldiers and a civilian.

The firm has applied for a fresh investigation into Surrey Police’s original investigation and the prosecution of the Guildford Four on the basis of material accessed at the National Archives at Kew.

The material, first identified by BBC Surrey, indicates “possible alteration or suppression of evidence relating to the admissions made by the Balcombe Street IRA Cell” in order to secure the conviction.

The firm has also now been granted access to the original inquest papers relating to the victims of the bombings.

A spokesperson for KRW Law said: “We are hoping to assess the significance of these papers in the coming weeks in order to determine whether there is sufficient reason to request the Senior Coroner for Surrey to resume the original inquests, which we understand would have been suspended pending the conviction of The Guildford Four.”