Blenheim Palace’s loos are a source of embarrassment, according to the Duke of Marlborough’s younger sister.

Lady Henrietta Spencer-Churchill told a podcast that she cringes when Americans come to stay at the estate’s outdated lodgings because there are no en-suite bathrooms or power showers – things our US friends value highly.

“On the private side, which is the East Wing, it’s always been lived in as a family home,” said Lady Henrietta, founder of interior design company Woodstock Designs.

“One thing I always find embarrassing is not having en-suite bathrooms or even shower rooms.

"Blenheim was not built to install plumbing. A lot of the floors and walls are solid - you can't just plonk a bathroom somewhere. You've got to think about drain-runs and where everything goes.

“So some people, especially the Americans, are horrified that they don’t get a bathroom en suite and they don't have a power shower.”

Lady Henrietta, 62, whose family have lived at Blenheim for 300 years, is the author of the book Blenheim and the Churchill Family.

She added of improvements: "We do things as and when we can. Although the rooms are large, they are cosy and very welcoming.

"They're not perfect by any means. They're quite shabby chic, a lot of the bedrooms, because we don't have the spare money to spend on doing them up."

President Trump and his wife Melania attended a black-tie dinner at the Palace with then prime minister Theresa May in 2018. However, they did not stay the night.