A spokesperson for ITV, which broadcasts the show in the United Kingdom, confirms to PEOPLE that the Oscar winner is participating in a short charity sketch set in the Downton Abbey world that will air "around Christmas time."
Alas, his character will not appear on the actual show, which premieres its fifth season Sept. 21 in the U.K. The actor, 53, will appear in a one-off sketch aiding the ITV charity Text Santa – an annual fundraiser which raises money for U.K. charities during the Christmas season. The skit will also not air in the United States.
Clooney, who reportedly plays a wedding guest, struck up a friendship with Hugh Bonneville, who stars as Downton's patriarch Robert Crawley, while filming The Monuments Men together.