Lord Grantham would describe it as the height of bad manners. American viewers have been urged to reject Downton Abbey's "silvered tureen of snobbery" by Simon Schama, the British history professor whose populist books have made him a New York celebrity.
Schama, professor of history at Columbia University, launched a stinging attack on Julian Fellowes, creator of the hit series, accusing him of peddling derivative plot-lines and historical inaccuracies to a US audience dazzled by anything set in a British country house.
Schama's assault arrived the day after Fellowes claimed a Golden Globe for the series, which has doubled the Sunday night audience for the American PBS channel.
Downton is the most popular British drama running on US television, gaining more than four million viewers, more than for some "prestige" US dramas, such as Mad Men.
After picking up his award, Fellowes said: "It's rather thrilling the way America sticks up for me." But writing in Newsweek, his fellow Brit shattered the consensus. "Downton serves up a steaming, silvered tureen of snobbery," Schama claimed. "It's a servile soap opera that an American public desperate for something, anything, to take its mind off the perplexities of the present, seems only too happy to down in great, grateful gulps."
Schama, who presented his take on the Edwardian era in the BBC series A History Of Britain, added: "Nothing beats British television drama for servicing the instincts of cultural necrophilia. So the series is fabulously frocked, and acted, and overacted, and hyper-overacted by all the Usual Suspects in keeping with their allotted roles."
He went on to admit: "This unassuageable American craving for the British country house is bound to get on my nerves, having grown up in the 1950s and '60s with a Jacobinical rage against the moth-eaten haughtiness of the toffs."
Fellowes, he said, has "gotten this stuff down pat since writing Gosford Park, though all the main plot-lines were anticipated a long time ago by Upstairs, Downstairs".
The dramatist, once described as "the biggest snob in Britain", has dismissed his critics as "socially insecure, left-wing nitpickers". But the influential historian will be tougher to shake.
Both Schama and Fellowes relocated to the US in the early 1980s. Diplomat's son Fellowes pursued his "toff appeal" as an actor, but after a series of roles on stage and screen, he found his true calling as a screenwriter with the film Gosford Park.
Schama became a Harvard professor at 35 and relayed his passion for America through a series of award-winning books and television documentaries. Transferring the accessible prose of books, such as his study of Dutch culture The Embarrassment of Riches, to the screen, he became the highest-paid historian on television. But his current series, The American Future, broadcast on BBC America last night, has yet to match Downton Abbey's popular appeal.
Fellowes, who made no secret of his desire to write more Hollywood scripts, shares Schama's fervour for the US. He recently said: "I suppose I believe in a mobile society, which I think at the moment America has got a better version of than we have." He was unavailable for comment yesterday.
A spokeswoman for Downton Abbey said: "It is a fictional drama series set in a well documented era of recent modern history. It is not a history programme, but a drama of social satire about a time when relationships, behaviour and hierarchy were very different from those we enjoy today. American audiences are presumably enjoying the latest series of Downton for the same reason as British audiences - it is an entertainment with an intertwined mix of romantic, dramatic and comedic stories delivered by a large ensemble of different characters and indeed, as with any popular TV drama series, offers an alternative to our own life experience."