Why is the bestselling book about to be responsible for soaring visitor numbers at some of Britain’s more obscure tourist attractions — ones that are not even referred to obliquely in Dan Brown’s famous text? The answer is that today the film camera is mightier than the book and both Belvoir Castle in Leicestershire and Burghley House in Lincolnshire are about to benefit from the new phenomenon of “set jetting”.

This week VisitBritain, the tourism agency, will start promoting Belvoir, Burghley and a number of other destinations as part of a £600 holiday trail of The Da Vinci Code film locations in Britain and France, entitled “Seek the Truth”.

They will be promoted in more than forty countries before next month’s worldwide cinema release of the film, which stars Tom Hanks, Audrey Tautou and Sir Ian McKellen.

VisitBritain works closely with film studios and offers similar tourist trails for blockbusters such as King Arthur, Master and Commander, Johnny English, Harry Potter and the Philosopher’s Stone and Notting Hill. Other maps exist for the London locations of several Bollywood films.

Enterprising Times readers can concoct their own film location tours using our handy map.

Tom Wright, the chief executive of VisitBritain, said: “The right film can be a giant advert — seen by millions of people — for the unique appeals of a destination. “We estimate around one in five of Britain’s international visitors are inspired to come here by the images they see in movies or on TV.

“Today, film tourism is a growing global phenomenon creating a new breed of tourist — the ‘set-jetter’.

Films have helped to showcase the essence of Britain’s varied destinations, our culture and iconic landmarks, as well as historic and contemporary characters. Given the worldwide popularity of the The Da Vinci Code, this is a fantastic opportunity to draw attention to all that Britain offers its visitors.”

Dan Brown’s book has sold more than 50 million copies and sparked a resurgence of interest in the Holy Grail, Opus Dei and the Knights Templar.

VisitBritain said that enthusiasts of The Da Vinci Code are exploring parts of Britain such as Lincolnshire and Leicestershire, traditionally less popular with visitors than Stratford-upon-Avon and the Lake District.

Lincoln Cathedral, which doubles as Westminster Abbey and is one of the finest Gothic buildings in Europe in its own right, is a highlight of the trail.

Burghley House, the 16th-century estate in Lincolnshire noted for its annual horse trials, becomes the Château de Villette in Versailles in the film. Visitors will be able to view the Heaven Room with its classical deities and Hell Staircase.

Next stop off may be Belvoir Castle in Leicestershire, home of the Duke and Duchess of Rutland, which stands in for Castel Gandolfo in the film.

The obscure chapel of Notre Dame de France in London interests visitors because of its mural featuring Grail and Templar images. Edinburgh is always a magnet for overseas visitors but until recently Rosslyn Chapel had not been high on the sightseers’ list.

Now its popularity is booming because the chapel provides the atmospheric setting for some of the most dramatic scenes in the book and film. Legend says that the Grail is concealed in its Prentice Pillar. There are also enigmatic carvings featuring symbols from Templar, Rosicrucian, Freemason and Grail traditions. Westminster Abbey is hardly off the beaten track but there is a developing interest in the Isaac Newton monument in the centre of the nave behind the high altar, which provides another valuable clue in the Grail mystery in the book. Some visitors may prefer to start their trip across the Channel in Paris.

The novel opens with the discovery of a death in the Louvre and the museum is home to the Mona Lisa, Leonardo’s most celebrated work.