You forgot Anneke Wills.
Apparently, Gatiss wanted to use Jean Marsh to play Sara Kingdom aging to death in a recreation of the climax of The Daleks' Master Plan, but the budget wouldn't run to it. Irony, really, considering she played the role all those years ago.
"What have you been doing since you stole that antique TARDIS of yours, since you first landed on Skaro? Shouting 'Look at me!!! I'm not fighting a war!', while you battle the Daleks all the way through space and time."