They are among 175 Britons, including dentists, lawyers, bankers and at least 20 other doctors, who “own” the the $200m (£106m) blockbuster film starring Tom Hanks and based on Dan Brown’s bestselling novel.

All belong to a syndicate put together by City financiers to buy the master print of the movie in a scheme designed by accountants to defer income tax payments for up to 15 years.

The group is almost as impenetrable as Opus Dei, the society allegedly dedicated to guarding the ancient secret revealed in the film.

“The film industry needs help, and a financial adviser suggested I join,” said Allamby, 47, who lives in a £500,000 stone cottage near Sheffield.

His group, Invicta Film Partnership No 23, has raised £125m, more than the cost of the movie, in the biggest ever sale-and-leaseback deal of its kind in Britain.

Sony, which made the film, will use about £15m of the money to promote the movie and to produce copies for the 9,000 cinemas showing it worldwide. The rest will be invested to pay leasing fees for the film it has just sold.

Such schemes raised £3 billion for the film industry last year, costing the taxman up to £1.2 billion in delayed tax payments.

Allamby refused to say how much he and Davidson, 43, had invested, but even though the movie opened last week to lukewarm reviews — “Opeless Dei” (The Sun) — the safety of their money is as cast iron as a Knight Templar’s armour.

Some 2m people are expected to see the film in Britain this weekend alone, while in Italy it has broken box office records despite the Vatican’s call for a boycott. The film earned €2m (£1.36m) there on its opening night, nearly double the previous best for the 1997 Holocaust drama Life Is Beautiful.

The jousting knight logo of Burberry, which once provided the trenchcoat worn by Audrey Hepburn in Breakfast at Tiffany’s, is also wielding its sword to help The Da Vinci Code. Christopher Bailey, 35, the label’s design director, has put in money to the partnership but refused to comment.

Matt Lorenzo, 47, the Sky sports presenter, was not as shy. “I have put in £50,000 and borrowed more from the bank,” he said. “ I am telling people I am now a Hollywood figure of some repute.”

If an investor puts in £50,000 and borrows another £200,000 to help fund a film’s post-production costs, the entire investment is put down as a tax loss. The Inland Revenue returns 40% or £100,000 to the investor who then has 15 years to pay it back as he receives annual leasing fees from the studio.

Gordon Brown, the chancellor, is so angry that a measure designed to attract filmmakers to Britain has been used as a tax deferral scheme that he has halted any more schemes unless filming started before April 1.

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