The US couples who bought their own slice of Downton Abbey

((C) ITV Plc/ CARNIVAL FILMS)

In downton abbey, a wealthy American heiress rides to the rescue of a British estate's hard-up owners. Now rich viewers in the US are being invited to buy their way on to the credits of the popular ITV series, in an attempt to fill the funding gap for quality British television drama.

When it airs on the PBS network in the US this week, the credits will be altered to include the names of four couples who have written substantial cheques to support the series. PBS, the commercials-free Public Broadcasting Service, was one of the original backers of Downton Abbey and has provided funding for a range of British dramas – including the recent BBC One revival of Upstairs, Downstairs, Sherlock and the Aurelio Zen mysteries.

BBC shows including Cranford were made possible by the funding PBS committed through its Masterpiece Theatre slot, which has showcased the best of British drama to US audiences for 40 years. But PBS, which relies on private financial support, has failed to attract a sponsor for the series since Exxon Mobil pulled out in 2004.

The broadcaster has now offered wealthy private donors the chance to become part of the Masterpiece Trust. For a sum in the region of £25,000 they can buy a guaranteed slot on the credits of Downton Abbey and other British shows. Rebecca Eaton, the series' executive producer, said: "We are very proud of the four couples whose names will be founding members of Masterpiece Trust – whose names will be on the show for the first time."

If British viewers are offered a similar opportunity, it is a move likely to find favour with Jeremy Hunt, the Culture Secretary, who wants to see more philanthropic gestures to fill the gap left by the Coalition's cuts in arts funding.

High-end drama is more expensive to produce than reality television. ITV was unable to meet the full £1m-per-episode cost of Downton Abbey, so NBC Universal, which owns Carnival Film & Television, its UK producers, provided a quarter of the funding.

Ms Eaton, who oversees the Masterpiece strand through the Boston station WGBH, has a significant influence over British drama production. "Cranford was on the verge of not happening," she once revealed. "But we mortgaged our financial future to get that done and it proved to be a great decision."

ITV said yesterday the first US transmission of Downton Abbey had doubled the PBS season's average audience, reaching 6.7 million people, making it the highest rated show Masterpiece has transmitted in recent years. The series, watched by 12 million people in the UK, will be extended to include a Christmas special when it returns this year.

Americans are keen to be associated with the programme after the first episode last week received rave reviews. Variety magazine called it "compulsively watchable from the get-go", while The New York Times said: "The cinematography is exquisite, and the attention to historical detail ... is as enticing as the characters."