Out, out,” chanted Jean Clément, as he performed a ceremony to rid a Parisian businessman of “negative spirits” supposedly conjured up by a jealous rival.

As the chanting went on, Robert — the “patient”, as Mr Clément calls him — appeared to have entered a trance-like state.

In his 50s, with purple circles below his puffy eyes so deeply indented that they look like bruises, he said he had been suffering from chronic insomnia and anxiety as his business goes through a bad patch.

He is one of a growing number of people in France who are turning to exorcists to save their careers or restore love to troubled relationships.

As he prepared for the exorcism, Mr Clément lit candles and incense and placed them beside a crucifix and semi-precious stones on a coffee table in the man’s elegant apartment.