A DESCENDANT of the family that founded Rosslyn Chapel has condemned the trustees of the medieval church for allowing it to be used in the film of The Da Vinci Code.

Dr Andrew Sinclair, a descendant of the St Clairs of Rosslyn, has claimed this will damage the reputation of the 15th-century building outside Edinburgh by giving credence to the “preposterous” claims made in Dan Brown’s bestselling book.

In The Da Vinci Code, which has sold more than 17m copies, Brown claims the Holy Grail was once hidden at Rosslyn and that the descendents of Jesus and Mary Magdalene can be traced to the gothic chapel.

Filming of the movie, which will star Tom Hanks and Audrey Tautou, is due to begin in September. Rose Line, the film’s production company, is understood to be paying the trust £7,000 a day for permission to film at the church.

However, Sinclair has condemned the book as “preposterous, its message pernicious, its history a bungle and a muddle”.

He added that the trust should have followed the lead of the church of St Sulpice in Paris and Westminster Abbey, which have refused to be involved in the film despite featuring in the book.

“As far as I’m concerned it is a load of rubbish,” he said. “It’s appalling. What it says about the grail and Rosslyn is absolute invention.

“The fact that St Sulpice has refused to allow anything to be filmed there because of the attack on the church is correct. Westminster Abbey has also refused.

“But Rosslyn has accepted and I think it’s a wrong decision. I would not lease the chapel, even for £7,000 a day, for anything so terrible for the reputation of Rosslyn as The Da Vinci Code.”

The former Cambridge University historian claims Brown’s assertion that the book is rooted in fact is particularly damaging. The novel’s protagonist is Robert Langdon, a Harvard professor.

“John Harvard (a key donor after whom the university was named) must be turning in his grave,” he said. “Mr Brown should have changed the name of the university, but using it is a way of implying that all this is provable. That is wrong.

“It damages every single reader who is persuaded that this fictional story of the Catholic church and Rosslyn is true.”

In his new book on the history of the chapel, published later this month, Sinclair will also reveal new research that he claims proves that the famous Apprentice Pillar — rumoured to contain the Holy Grail — could not do so.

Last night Graeme Munro, vice-chairman of the Rosslyn Chapel Trust, defended the decision to allow the production company access.

Detailed plans were submitted, he said, assuring them the chapel and its visitors would not be inconvenienced. Proceeds will help fund a £3m renovation project.

“Many of the stories surrounding Rosslyn are highly speculative. The trust would not subscribe to the legends presented by The Da Vinci Code,” said Munro.

Times Recommends

• Phoebe Caldwell wins Times/Sternberg Award
• Raging against fake pop has its own pitfalls
• How a voice for everyone led to stalemate