Gambon, Jenkins to appear in 'Who' special

Sir Michael Gambon and Katherine Jenkins will appear in this year's Doctor Who Christmas special.

Showrunner Steven Moffat previously described the 60-minute episode as "the most Christmassy Christmas special" yet, reports The Guardian.

69-year-old Gambon most recently completed filming his role as headmaster Albus Dumbledore in the Harry Potter series.

Moffat said: "Michael Gambon is as distinguished an actor as I can imagine and the fact that he was Dumbledore means that he is already known to millions of children."

Classical singer and Popstar to Operastar judge Katherine Jenkins will also star in Matt Smith's first Christmas outing as the Doctor.

Speaking about Jenkins, who previously made a cameo appearance as herself in Emmerdale, Moffat said: "She is brilliant – she is a great singer and a great performer."

Writing on Twitter the 30-year-old confirmed that filming began today.

"I can now tell you my news. This Xmas in the year 2010 I will be joining the Time Lord in the Tardis. Filming starts today. Wish me luck!" she wrote.

Catherine Tate, Kylie Minogue and David Morrissey have been among the guest stars in previous Christmas specials.

It was previously reported that the script for the episode had gone missing.