The force of Star Wars is such that even actors who faces were never seen on screen are idolized by fans across the world.

In his new documentary film Elstree 1976 Jon Spira explores this extraordinary phenomenon by tracking down and putting centre stage actors who had bit parts in A New Hope, which was largely filmed at Hertfordshire's Elstree Studios.

Resolutely not a 'making of Star Wars' documentary, it explores what the actors lives have been like in the decades since the film came out and whose characters' fame often seems to eclipse their own.

It stars the likes of Darth Vader actor David Prowse, rebel pilot John Chapman, Stormtrooper Anthony Forrest who famous said the line "These aren't the droids we're looking for", Garrick Hagon who portrayed Luke's childhood friend Biggs Darklighter actor and Pam Rose who portrayed an alien in Chalmun's Cantina.

Few of them understood the impact George Lucas' original trilogy would go on to have culturally on a global basis.

Jon says: "Whilst teaching screenwriting at Oxford Film and Video Makers Workshop, I had a student called John Chapman, a twinkly-eyed guy, about my dad's age who one day revealed to me that he had been an X-wing pilot in Star Wars.

"As we talked more about it, I learned that he was only visible on screen in one shot, but you couldn't see his face.

"The real mind-blower was that despite this incredibly brief appearance, he was attending sci-fi conventions and selling autographs to rabid Star Wars fans.

"This opened the door for me to this incredible community made up of a hierarchy of everyone from very well-respected actors who had appeared in small roles in the film early in their career, to professional film extras, right the way to people, like John, for whom a few days on Star Wars in 1976 was their only ever brush with Hollywood."

He joined forces with producer Hank Starrs, director of photography Sonny Malhotra and sound recordist Sherylee Houssein to make the Kickstarter-funded film and travelled across the UK, to the east coast of Scotland to interview X-wing pilot Angus Macinnes and all the way down to Dorset to film Paul Blake, better known as Han Solo's contentious kill Greedo.

Jon says: "What we have ended up with is a collection of incredible interviews with fascinating people. Although I have no doubt the Star Wars fan base will hoover up all of the new information and perspective this film will present, the truth is that you don't need to even have seen Star Wars for this film to connect.

"It's a portrait of ten everyday people, linked by this one shared experience, whose lives led them far away from it but then brought them back together by the power of the fan's will."

Elstree 1976 will be screened as part of the BFI London Film Festival at Picturehouse Central on Friday, October 9 and Cineworld Haymarket on Sunday, October 11.