Martin O’Rawe, 70, brought an appeal following last year’s landmark UK Supreme Court ruling which found that Mr Adams was detained unlawfully and therefore had not broken the law by attempting to escape.

It follows a similar appeal brought earlier this year by Ivor Bell, 84, who also succeeded in overturning his convictions for helping Mr Adams.

The Supreme Court unanimously held that the interim custody order (ICO) made in respect of Mr Adams in 1973 was invalid because it had not been considered by a Secretary of State.

Mr Adams brought the appeal following the publication under the “30-year rule” of a legal opinion from JBE Hutton QC (later Lord Hutton of Bresagh), dated 4 July 1974, that the making of an ICO required the personal consideration of a Secretary of State.

Delivering judgment in the Court of Appeal, Mr Justice Seamus Treacy said: “In light of the foregoing we are not satisfied as to the safety of both convictions.”