Tony Gilroy has described the development of the Bourne film franchise as "a shambolic success".

Gilroy - who has written all four Bourne instalments and makes his franchise directorial debut on The Bourne Legacy - spoke with Vulture about the series' chaotic journey.

"It's been somewhat well documented that [the Bourne franchise] not been well organised; it's not been the space programme," he said. "It's been a very shambolic success.

"Still, there's something about the DNA that got started in the beginning . . . there's been an integrity to it, and I think having Matt Damon pin that integrity down and having Doug Liman's funky, dirty-on-the-ground filmmaking and Paul [Greengrass's] journalistic integrity, that's helped.

"As bent and crazy as the process got, and as many people didn't get along, no-one ever tarnished that basic element of truth, and that's been the one thing that's held it together."

Damon played the eponymous lead Jason Bourne in the first three films, and is replaced in The Bourne Legacy by Jeremy Renner as new agent Aaron Cross.

The Bourne Legacy will be released on August 13th.