By the way, as far as RTD is concerned, Dalton's character is Rassilon. He's stated this on many occasions, including DWC and The Writer's Tale. Unlike Bloom's character, where he said "well, personally, I think she's the Doctor's mother, but let the fans go crazy". He's unambiguously Rassilon from Rusty's POV... and as he's the writer and executive producer of the episode, his opinion holds a lot of sway. ''''''