Letters sent by the British military in Berlin also accuse Hess's Soviet guards of mental cruelty. Several times in the 1970s, British officials tried to persuade the Russians to try to persuade them to release Hess or relax his harsh conditions. But each time they were rebuffed.
The story of Rudolf Hess is one of the strangest to emerge from the Second World War.
The former First World War soldier, who joined the Nazi Party in 1920, was captured after flying alone to Scotland in May 1941 to seek an Anglo- German peace deal. Hitler said he had gone mad, but Josef Stalin, the Soviet dictator, suspected some sort of deal was being done with Britain and Nazi Germany, hence the later rough treatment.
In 1946, Hess was sentenced to life at the Nuremberg war trials and later transferred to Spandau in the British-controlled sector of Berlin. The four occupying powers, the US, Britain, France and the Soviet Union took turns to guard him.
After 1966, when Baldur von Schirach, the Hitler Youth leader, and Albert Speer, Hitler's armament minister, were released, Hess was alone. By 1974, several governments, including Britain, America and France, were calling for his release on humanitarian grounds.
The correspondence, released under the Freedom of Information Act, shows the Queen wrote to the former German chancellor, Willi Brandt, saying Britain was doing all it could to try to free him. These efforts were stepped up as Hess approached his 80th birthday. But by May 1974 all hope had faded. Of pressing concern was the increasingly cruel treatment by the Soviets.
In a letter by a senior official in the British Military Government to the British ambassador in Bonn paints a particularly bleak picture. Robert de Burlet, who had diplomatic responsibility for Spandau and visited Hess several times, wrote: "now that the possibility of a tripartite demarche to the Russians to appeal for Hess's release ... seems to have receded ... I think I should bring up to date on the current situation at the prison."
Mr de Burlet said the Russian governor at Spandau has demanded that Hess be deprived of his glasses between 10pm and 7am every night. The Russians also insisted Hess burn his notebook before being allowed a new one, restricted his access to the prison garden and refused him physical contact with any visitor, including his wife and son.
Mr de Burlet wrote: "This new Russian turn of the screw, is particularly unpleasant and amounts to the infliction of mental torture on the prisoner. It is made more blatant by the fact that since November 1959 when Hess cut his wrists with a fragment of glass from his spectacles he has been given ones with plastic lenses."
Mr de Burlet says that in the "course of argument" with the Soviet governor, whom he describes as "short, fat and sinister", he pointed this out but "he refused to listen".
He adds: "It is strange but true, that the Allies, and in particular the British, now have a dual role at Spandau. On the one hand we are carrying out the sentence passed on Hess and on the other hand we are additionally forced into the role of his protectors against the grosser Soviet violations of his minimal privileges.
Mr de Burlet goes on: "We might, of course, tell the Russians to go jump in the Volga ... but this might lead to violent protests and ... physical confrontations with the Soviet warders."
Hess hanged himself at 93, having been a prisoner for 46 years, 40 of them in Spandau, the last 23 in solitary confinement.Reuse content