Picture the scene: Lord Grantham and George Clooney putting the world to rights over gin gimlets served by Carson in the Downton drawing room, with Lady Mary stealing covert glances at the handsome house guest and the Dowager Countess looking on, purse-lipped.
Yes, Hollywood royalty is coming to Downton this winter in the form of Mr. Clooney himself.
The Oscar-winning actor will appear in a sketch for the Christmas special of the hit ITV show and has already filmed the scenes in question, a Downton spokesperson confirmed to the Guardian.
He will not act a full episode, the rep said.
The 53-year-old actor will play an American guest attending a wedding on the country estate, according to The Sun, which first reported the news.
"This is the biggest moment in Downton history and shows it's now the biggest drama in the world," a source told the newspaper. "All the plans have been shrouded in secrecy because George was determined for his role not to leak out."
Hugh is close friends with George - the pair starred in Nazi war drama The Monuments Men earlier this year - and it seems that he helped orchestrate the cameo for Downton during their time filming together.
"George and Hugh [Bonneville, who plays Lord Grantham] became really close during filming and it became very clear that George loved Downton," said the source.
"He would joke around about the idea of getting a part so Hugh helped put the wheels in motion to make it happen."
Earlier this year George was spotted at Highclere Castle, where the award-winning series is set, prompting rumours that he was thinking of marrying his fiancée Amal Alamuddin there. The couple are said to be huge fans of Downton.
But as it turns out, the story may have been an elaborate ploy to mask the fact that the Hollywood star was prepping for a guest role in the show instead.
His appearance will tie in with a Christmas fundraiser called Text Santa for ITV and all money from the episode will go to charity.
With their impending nuptials shrouded in secrecy, speculation has been rife as to where and when George and Amal, a 36-year-old human rights lawyer, will tie the knot.
People magazine said the actor may have let slip the location of the ceremony at an event in Tuscany this weekend.
Taking to the stage to accept a humanitarian award, he apparently told the crowd: "I met my lovely bride-to-be here in Italy, whom I will be marrying, in a couple of weeks, in Venice, of all places."
Previ0us reports suggested that the couple would get wed on Clooney's estate in Lake Como.
Series five of Downton will return to ITV on 21 September. All the familiar faces will be there - Ladies Edith and Mary, Lord and Lady Grantham, the Dowager Countess, Mr and Mrs Bates, Carson, and so on - along with guest appearances from Richard E Grant and Anna Chancellor.
And now we have George Clooney joining the fray as well.
His appearance is a huge coup for the ITV show and we can't wait to see him frivol with the likes of Cora Crawley and co. over Christmas turkey and a glass of cognac.
Photos: Rex Features and ITV, words: Anna Brech