Rupert of the Rhine
From Tardis Wiki, the free Doctor Who reference
Prince Rupert of the Rhine was the leader of an 18,000-man strong army that fought against Oliver Cromwell at Marston Moor in the English Civil War. He was soundly defeated. (PROSE: Nightshade)
Behind the scenes
Mark Gatiss did not call Prince Rupert "Prince Rupert of the Rhine" explicitly — perhaps because that's such an obvious fact of English history. However, even if Prince Rupert was not sufficient to identify him by itself, it is stated that Charles I is Prince Rupert's uncle.
