Over the course of Season 16, Romana begins to take on some of the characteristics of the screaming "damsel in distress", which reinforced Tamm's decision not to remain in the role as she felt the character had been taken as far as she could go [REF].
Although Tamm had left the show on relatively good terms and was willing to film a regeneration sequence for the start of Season 17, she was not invited to do so [REF].