Mike Holmes, who has volunteered there for 13 years, said those in open revolt were not homophobic, but simply annoyed that the Trust had strayed beyond its role as guardian of the country’s heritage.

“Wyndham would have turned in his grave to know what’s happening,” Mr Holmes, 72, said. “He was an intensely private man. He was never open about his sexuality.

“The National Trust looks after grounds and buildings, they do not have the right to research their benefactor’s private lives to suit the needs of a marketing campaign. It’s abhorrent.

“This is not about the squire’s sexuality, I am not homophobic and that’s not what this is about.

“I love Felbrigg Hall, and I think nobody could say the volunteers aren’t the greatest advocates for the place.