Kris Marshall has been cast to follow Peter Capaldi as BBC's Doctor Who, according to The Mirror, which isn't always a reliable source of information. The mirror report that according to an undislosed source, "Kris Marshall has already joined the cast and will regenerate at the end of this series, not in the Christmas special."
Doctor Who returned on the BBC this past Saturday for its tenth season following the 2005 revival. We already know that this will be the final season for both Capaldi and showrunner Steven Moffat as reported at the end of January. Filming for the entire series is already complete.
When asked about Marshall's reported casting, a BBC spokesperson reportedly told The Mirror that "no casting decisions have yet been made on series 11."
The 43-year-old actor is perhaps best known for his role as Nick Harper in My Family as well as Colin Frissell in 2003 hit film Love Actually, and has reportedly been selected as the BBC want another Doctor similar to David Tennants.
It would be no surprise if the BBC have already cast a new Doctor, given that the trailer for series 10 clearly shows Capaldi regenerating. Capaldi has also reaffirmed that the Christmas Special will be his last episode, which leaves two scenarios. The regeneration is a cop-out, or the new Doctor meets up with his previous self which we've seen happen a few times since Doctor Who started 1963 and always leads to fun TV - so let's hope that it's the latter.
Of course, until the BBC announce anything, nothing is official, and they're usually pretty good at getting out casting decisions either before anyone else has a clue or shortly after rumours start flying.