I always believe Hess went to England on Hitlers orders.
Hess didnt take a dump unless the Fuhrer told him to.
Hess was not locked up in solitary; in Spandau prison, kept by the allies for the imprisonment of the highest-level war criminals, Hess was in what we would call "general population" and could socialize with the others. In later years (I think, after Albert Speer and Baldur von Shirach were released in 1966), he was alone, only because he had a life sentence and everyone else had been released.
Source: Spandau: The Secret Diaries, by Albert Speer. I can't pull quotes from it just now as it is out on loan.