As a side note, Gawn Grainger, who played Stephenson in Mark, is reported to have died.
The original idea was that the Doctor rather than Beyus stayed behind and got killed at the end.I know Colin (rightfully, in my opinion) refused to film a regeneration story, but was that story what Time and The rani became? I just don't see how it would work, would 6 have had the same semi amnesia the whole story until something causes him to regenerate at the end, or would the story have played out more like a normal Doctor vs Bad Guy story without doing the "Rani messes with The Doctors head" bit?
Regardless I'm glad he wasn't there, bad enough he had the worst first story of any doctor, I'd have hated for 6 to go out on such an awful story (even if it would have been different then what 7 got, I doubt anything would have saved the story).