Who was the last prisoner to be kept in the Tower of London?

Yes, Rudolph Hess was the last political prisoner, he stayed in the Tower for 4 days in 1941.



In 1952, however, the Kray twins were held in the Tower for 4 days for failing to report for national service, making them amongst the last prisoners of the Tower of London.



http://www.castles.me.uk/history-of-towe
I think it was Rudolph Hess, for a brief period.