Nothing links the Cathars to Bérenger Saunière – and come to think of it, there's nothing to show that Pierre Plantard or Philippe de Chèrisey ever referred to the Cathars (or to the Holy Grail).

Christian Attard has recently implied that the 1945 French film La fiancée des ténèbres, shot in Carcassonne, could have been responsible for inspiring Philippe de Chèrisey, with its elements of a coded parchment, the tomb of a nobleman, an underground cathedral and the Holy Grail. Its screenplay after all was written by Gaston Bonheur, who was interested in surrealism and this could have been another factor involving Philippe de Chèrisey!

Alas, Jean-Luc Chaumeil possesses correspondence dating from the 1960s between Pierre Plantard, Philippe de Chèrisey and Gérard de Sède showing that what inspired the creation of the “Saunière parchments” was the popularity of the Dead Sea Scrolls, that were hidden in caves. Nothing to do with a 1945 French film.

As for Bérenger Saunière and Catharism – Saunière was antagonistic towards it when it tried to establish itself in Rennes-le-Château in 1896.

The Occitan newsletter Mont-Segur began circulating in Rennes-le-Château in 1896, celebrating the achievements of the Cathars and denouncing the Crusade. It was established by banker Arthur Cassou and the Occitan poet Prosper Estieu. Estieu was the village schoolmaster in Rennes-le-Château from October 1899. He was also a member of The Gnostic Catholic Church shortly from before 1900, through which he got to know Déodat Roché (the two of them met each other in Rennes-le-Château for the first time on 2 August 1900).

Saunière deprived the village school of its water supply from his water tank in 1900, forcing Prosper Estieu to obtain water for the school from elsewhere.

In February 1903, the Mayor of Rennes-le-Château wrote an official complaint to the Prefect of the Aude saying Estieu was a very bad teacher – the Sub-Prefect later suspected (on 15 February) whether or not that letter, not in the Mayor's handwriting, had really been written by Saunière.

Saunière signed a formal complaint against Estieu in July 1903 – forcing him to quit Rennes-le-Château in August 1903 to move to Raissac-sur-Lampy.

Therefore, there is nothing linking Bérenger Saunière with the Cathars.