I realised very early on that he doesn’t like a structured set up. He’ll get on with what he’s doing and it’s up to me to cover it. There was a point when I thought, this is a completely vampiric, necrophile experience.” Petit admits, “Normally the way Iain and I work is not as fraught as that There’s no sense of competition. It’s one of the rare documentaries, or quasi-documentaries, that could leave you not just questioning the film-makers’ sanity, but your own.”We knew we were crossing boundaries between fact and fiction,” Petit says. There was a sense of personal danger to the film as it unfolds – all that kind of magic stuff which Peter and Iain shared. The Falconer (1998) was ostensibly a portrait of Sixties film-maker and Rolling Stones chronicler turned bird-fancier and would-be magus Peter Whitehead.

“Peter Whitehead is in a way a myth-maker, so he didn’t seem to be actively discouraging that. A narrative of arcane dealings, disappearances and espionage combined Petit’s footage with a mass of archive material, further processed by artist Dave McKean’s delirious video manipulations. I did quite a lot of research into Dulles: he was working in neutral Switzerland, meeting the world’s bankers during the war, he’d previously invested money for American clients into the Third Reich, so to put him in a room with Heinrich Himmler wasn’t a big jump. That meeting never took place but, in the way that Don De Lillo talks about history coming down to people talking in rooms, it’s not such a stretch.” The same paranoid fiction-building energy goes into Petit’s TV collaborations with Iain Sinclair, London’s peripatetic sage and fabricator of arcane crypto-histories. They fixate on those outsider figures, whom Sinclair calls the “revenants,” the “reforgotten”, a heroic legion among which Petit might justifiably count himself.The duo’s first collaboration The Cardinal and the Corpse (1992) traced links between the east-end underworld, the second-hand book trade, and lowlife novelists such as British Bohemia’s louche phantom Robin Cook aka Derek Raymond Later essays were lawlessly equivocal.

Their collaborations are not just genre-bending, but attempt to mess with the fabric of reality, to rewrite cultural history. They make an odd team: at once the Grumpy Old Men of experimentalism, issuing passionately oblique jeremiads against Britain’s cultural decay, and enthusiastic refuse collectors, salvaging banished refuseniks and giving them air-time (or Asylum, as one film was called). In a zigzagging narrative as byzantine and as blackly pessimistic as late James Ellroy, Petit explores covert connections between the former CIA head Allen Dulles and the Nazis.”One of life’s better remarks,” says Petit, “is ‘Follow the money’. “I just clocked in every day and explored the building and thought, this would make a really good location for a book. Basically, it was my attempt to do Celine’s Journey to the End of the Night. I took his character Robinson, the person who’s always ahead of the narrative, so in that sense it was a straight steal.” Petit side-stepped with The Psalm Killer, a huge, densely-researched thriller about serial killing in Northern Ireland, which narrowly failed to make him a surefire brand name, a British Thomas Harris.Another Irish-themed novel, The Hard Shoulder, was more like latterday Patrick Hamilton, a coolly melancholic tale of a hard man’s return to boarding-house Kilburn, while Back From the Dead was a mystery novel internally sabotaged by a key character apparently being a ghost.Petit’s most ambitious thriller yet is The Human Pool (2002), a vast secret history of the Second World War.