The one where Leela and K-9 decide to stay behind on Gallifrey...
Two minutes in to the sixth episode, Sontaran Commander Stor finally takes off his mask... and, as suspected, it wasn't worth the wait. The mask is an ill-fitting travesty of previous Sontaran masks, it isn't even attached to Derek Deadman's face around the eyes or nose. Coupled with Deadman's painfully poor performance (his delivery is slow, rasping and leaden), the whole Sontaran experience is disappointing. Deadman might be right for the part in that he is short and stout, but other than that, the guy just can't act. This is the sort of actor more accustomed to roles such as "Man at telephone box", "Knicker snatcher" and "Second porter". Playing a potato-headed Doctor Who monster might not be up there with Hamlet or King Lear, but Deadman does not have the talent required to play a convincing villain in a rubber mask. Kevin Lindsay did. Derek Deadman does not.
He can't even put his helmet on correctly, plonking it on his head skew-whiff in a moment that made me burst with laughter. Derek Deadman's Stor is a laughing stock.