One of the most high-profile and potentially far-reaching copyright cases seen in the English courts recently will start this morning, with two authors of a non-fiction book suing Random House, publisher of Dan Brown's best-seller The Da Vinci Code, over alleged infringement.

Michael Baigent and Richard Leigh are claiming that the American author's novel appropriated themes and ideas that they explored in a 1980s work called The Holy Blood and the Holy Grail.