Downton Abbey’s international success has attracted big-name guest stars throughout its run, with actors such as Shirley MacLaine and even George Clooney popping up in the period drama.

One of the ITV programme’s biggest signings was Shirley, who first graced the Downton estate in series three when she took on the role of Cora’s mother, Martha Levinson.

Adding to the American contingent was Paul Giamatti, who arrived in the show for the 2013 Christmas special as another of Lady Grantham’s relatives, her brother, Harold Levinson.

Downton Abbey Maggie Smith and Shirley MacLaine
Shirley MacLaine with Maggie Smith in Downton Abbey (ITV)

A year later, the festive episode welcomed another special guest – Alun Armstrong, who played the butler at the home of a family the Granthams were visiting, who was far from being full of Christmas cheer.

Richard E Grant featured in the latest series as art historian Simon Bricker, who came to view a painting at Downton and while he was there took a shine to the lady of the house, Lady Grantham Cora Crawley (Elizabeth McGovern).

Four Weddings And A Funeral star Anna Chancellor also cropped up in series five as the amorous Lady Anstruther, who had tracked down Jimmy Kent (Ed Speleers) the footman from a previous job and tried to pursue her passion for him.

Downton Abbey Elizabeth McGovern and Richard E Grant
Richard E Grant in his Downton Abbey role with Elizabeth McGovern as Lady Grantham (ITV)

One of the drama’s most controversial guest stars was EastEnders favourite Nigel Harman, who played visiting valet Mr Green, a sinister character who raped show regular Anna Bates (Joanne Froggatt) which led to viewer complaints to both ITV and Ofcom. Mr Green later died in a suspicious accident which appeared to be linked to Anna’s husband John, played by Brendan Coyle.

Other guest appearances have come from Robert Bathurst, Samantha Bond and MyAnna Buring.

But by far the most talked-about Downton guest was an A-lister who joined the cast for a one-off charity sketch – George Clooney.

Downton Abbey George Clooney and Hugh Bonneville
George Clooney and Hugh Bonneville on the Downton set (Nick Briggs/ITV)

He set hearts aflutter among the regular stars when he arrived to play George Oceans Gravity, Marquis of Hollywood, in a Christmas sketch for ITV’s Text Santa appeal and tried to kiss Dame Maggie Smith’s Dowager Countess.

George also starred alongside Joanna Lumley in the mini-episode, who played an angel showing Lord Grantham (Hugh Bonneville) what would happen if he fell into financial ruin, as well as Jeremy Piven who made a cameo as Mr Selfridge from ITV’s other hit period drama.