By Dominic Casciani BBC News
The documents show British governors fought Soviet attempts to turn the jointly-run jail into a "gulag" labour camp with just one prisoner.
Hess had been in custody since flying to Scotland in 1941. Marginalised in the Nazi hierarchy with increasing mental problems, he thought he could strike a peace deal with Britain so Hitler could invade Russia unhindered. He ended up jailed for life at the Nuremberg war crime trials.
In one meeting, de Burlet demanded the Russians see sense.
"If you keep him in prison until he dies, you have created a martyr who would be remembered not for his own misdeeds but for the inhumane treatment which he himself suffered."
The Russian governor began censoring large parts of Hess's letters to his wife. He ordered his guards to take Hess's glasses at lights out - a regulation that was never followed by the other powers.
When a Russian guard established that Hess had 13 photographs in his cell, rather than the regulation 10, three were removed - leading to another row in the governors' office.
Hess wrote himself a sign reminding himself to stand up in the presence of the Russian commandant. The three other powers said they didn't want an old man to stand.
Within days, the incident had escalated into a full-scale row between the four governors with the Russians accusing the British of breaching the original post-war agreement over war criminals and demanding reports and disciplinary action.
"We have what I consider a genuine case of mental cruelty," said Robert de Burlet.
"Whatever horrors the Germans had perpetrated in their concentration camps I do not want it to be said that we were following their example."
London urged him to resist attempts to tighten the regime and diplomatically endure lecturing from Russian generals, one of whom was frequently the worst for drink.
Hess's birthday passed with no sign of movement on release. And in a sarcastic editorial marking the occasion in Pravda - the Kremlin's official newspaper - explained why.
"The Hitlerite lieutenant must drink his retribution to the bottom of the cup," it said.