In town to promote Michael Clayton, his 2007 legal drama that saw him nominated for two Oscars, for best director and best screenplay, the eight-year saga writing the three scripts for The Bourne Identity and its sequels was behind him at last. "I don't really want to talk much about the Bourne process," he groaned, memories flooding back of the "insane" period of his life that arguably contributed to the grey hairs now adorning his head.
Today, he's got little choice. Sitting in London's Claridges hotel, the erudite 55-year-old is here to promote The Bourne Legacy, the fourth in the series, his first as both writer and director and – crucially – the first without star Matt Damon, who so memorably played amnesiac CIA agent Jason Bourne. "It wasn't something I ever thought I would do," he says. "It wasn't on my wish list. I left after the beginning of [2007's The Bourne] Ultimatum. I gave them the script, left and went off and did Clayton. I left all that behind for years. So it wasn't a burning desire to come back and do this."
In the interim, studio backers Universal tried to figure out a way to continue a franchise that had already grossed $944million around the world; not easy when "they'd wrapped up the package so tightly", says Gilroy. With Bourne's story effectively at an end, it was "a very difficult writing problem. And I think a lot of smart people worked on it for a long time – they couldn't figure out what to do, and everybody walked away." With Damon quitting the series, so did Paul Greengrass, who directed Ultimatum and its predecessor The Bourne Supremacy.
Which left an even more intriguing problem: how do you make a Bourne movie without Jason Bourne? That's when Gilroy took the meeting. "I started off just playing it as a game, then got a little more involved, figuring out a story. It kept getting more interesting to me as we went along." His solution is an elegant one. Rewinding to the events of Ultimatum, with Bourne still at large but now in the backdrop, the CIA brass decide to ruthlessly shut down the programme that trained Bourne, assassinating every agent on the ground.
"The really difficult magical part was finding a character that was as interesting and has a fundamental an issue as Jason Bourne did," says Gilroy, who ultimately settled on creating Aaron Cross. Played by Jeremy Renner (MI:4, The Avengers), Cross is another trainee agent. But unlike Bourne, he is not afflicted with amnesia, and knows exactly who he is. His "problem" comes when he narrowly escapes a CIA attempt on his life in the Alaskan wilderness and must go on the run to figure out why the people that nurtured him are now trying to kill him.
Much like the preceding three films, The Bourne Legacy doesn't even pretend to be loosely based on the source novel (written in 2004, it was the first of seven spin-offs by Erin Van Lustbader, penned after Bourne creator Robert Ludlum died). "I never read any of the books," says Gilroy. "It's been in name only since -[after] the first 20 minutes of The Bourne Identity." This typifies the ad-hoc approach taken on the earlier films, which may come as a surprise given how polished the resulting franchise was.
"If you told anyone who worked on the first movie there would be a sequel, you would have been laughed out of the room," says Gilroy. "It was just such a crazy endeavour." Re-writes, re-shoots and clashes between the studio and Identity director Doug Liman made it a strained production. Forced to fax new scenes to the set every day, little wonder Gilroy calls it "a very shambolic road to success". It certainly explains why Gilroy – whose previous writing credits included Armageddon and Proof Of Life – had no wish to discuss Bourne when we last met. "[Back then] It was very much in my rear-view mirror," he says.
Still, he must take some pride in being a part of a franchise where the success is not just about box office numbers. The Bourne franchise's approach to action – notably the close-quarters fight scenes – has become so influential in Hollywood, even the James Bond producers were forced to re-think their strategy. Gilroy allows himself a smile at this. "What I really love is when all my screenwriter friends started coming back and going 'God, dude, I just took this friggin' meeting and all they want me to do is do Bourne!' It's torture to them, and that gives me the most pleasure!"
He is joking, of course, but while Gilroy may have turned director since Michael Clayton (he followed it with 2009's Duplicity, with Julia Roberts), he still has a lot of feeling for writers. His mother Ruth was a sculptor and writer, while his father Frank D. Gilroy was a playwright who won a Tony and a Pulitzer Prize for his 1965 play The Subject Was Roses and later turned to directing, beginning with Shirley MacLaine drama Desperate Characters.
Gilroy and his two siblings could not help but be influenced, even though the family moved from Hollywood to upstate New York. "Somehow everybody floated back," he says. While brother Dan is also a screenwriter, and co-wrote The Bourne Legacy, John is an editor, who has cut all three of Gilroy's movies, beginning with Michael Clayton. Understandably, their father – now 86 – is delighted that Bourne has become a Gilroy legacy. "He's very proud that we are working together."
Of course, the film does leave one tantalising question: will we see a fifth instalment, featuring Cross and Jason Bourne? You could even call it The Bourne Betrayal, after the fifth Bourne book. Gilroy groans. "There's been nothing so far other than bar talk -there's no master plan whatsoever. Could you make a story that way? You could. But I could give you 25 different ways we could go forward." Like a very lucrative millstone, Bourne's going to be hanging around his neck for many years to come.
The Bourne Legacy opens on August 13.