Says the official Doctor Who site, David Tennant and Billie Piper will switch on the Christmas lights in Cardiff this year. "Santa has an early present for Cardiff-based Doctor Who fans this year. 17 November sees the Welsh capital's own Christmas Invasion as Billie Piper and David Tennant arrive to turn on the festive lights. Seasonal celebrations begin at 5.45, with the Red Hot Santas taking to the stage to play some Christmas favourites. The big switch on by the Doctor and Rose happens at 6.45, after which visitors can move on to the City Centre and shop until 8pm. Or they can get their skates on and head to the open-air ice rink at Cardiff's Winter Wonderland, which opens its doors to the public at 7.45pm."