I read a couple of reports about this last night but i seems more and more likely that this is not just some rumour. If Jenna was playing a big role like Queen Victoria then it would use a lot of her time up which would be hard to work with Doctor Who as well.
Though this rumour does come from The Mirror here
Jenna – who plays time and space-hopping Clara Oswald – has landed a major role as Queen Victoria in a £10million ITV drama.
She is thought to have already filmed her final scenes for the hit BBC1 show, and will bow out before the Christmas special.
Earlier this week Jenna was asked how long she would stay and told the Radio Times: “You’re in Doctor Who knowing it will never last.