Downton Abbey fans have been given a glimpse of what is to come in the drama's Christmas special.

ITV is screening a two-hour episode, set in 1924, which will feature New Tricks actor Alun Armstrong and Blind Justice actress Jane Lapotaire as guest stars.

The story - featuring regular cast members such as Dame Maggie Smith, Hugh Bonneville and Michelle Dockery - will see the Crawley family at a grouse shooting party at Brancaster Castle.

Rose's (Lily James) father-in-law, Lord Sinderby, has rented out the Northumberland castle and invited the family.

ITV said that Armstrong's character Stowell, who is butler to the Sinderby family, "has an axe to grind and a scandalous secret threatens to undermine the holiday.

"Surprises are in store as the families become better acquainted with each other and some new faces arrive on the scene."

The drama will feature the servants "holding the fort back at Downton", with Anna (Joanne Froggatt) facing an uncertain future behind bars and Bates (Brendan Coyle) taking "drastic measures in a bid to clear her name".

James Faulkner and Penny Downie will return as Lord and Lady Sinderby, along with Matt Barber who plays Atticus Aldridge in the special, which is expected to air on Christmas Day.

Alnwick Castle in Northumberland was used as the location for Brancaster Castle.