"We thought it would be really easy as half the job would be done – it would just be an edit job. It turned out to be far more difficult than we had anticipated...”

Watching Terence Davies’ The Time and the City, which tells the story of growing up in Liverpool through archive footage, inspired film-maker Paul Kelly and long-time collaborators Paul Wiggs and Bob Stanley of Saint Etienne to make their own archive film of London.

The trio had worked together on three Saint Etienne-soundtracked films about modern London – starting with the extended music video for the band’s 2003 album Finisterre, covering hidden places in London. Two years later they were commissioned to make What Have You Done Today Mervyn Day? about the pre-Olympics wasteland of the Lea Valley, and then 2007’s This Is Tomorrow concerning the regeneration of the London Festival Hall.

The initial plan for How We Used To Live had been to cover the last 100 years across five London boroughs to see how they had developed.

But when Julien Temple released his archive documentary London: The Modern Babylon, in 2012, the team had to rethink their original plans.

“A lot of the footage from the BFI Archive that we really liked was in colour,” says Kelly.

“Colour film footage was introduced in the 1950s, and it ended with the advent of video in the 1980s, so that set our parameters.

“The BFI has a vast collection of public information films, British transport films and travelogues encouraging people to holiday in Britain. If we had the BBC library it would have made a very different film.

“Having those restrictions presented a challenge to us, but it’s nice to have confines in a sense – it’s like having a deadline. If the London Film Festival hadn’t agreed to show it before they saw it last year we would still be working on it now.”

Researching the archive proved to be the most time-consuming activity – as Kelly realised the difference between being able to go out and shoot a specific location compared to finding that same spot across reels of film.

“We imagined certain shots existed, but when we started looking we couldn’t find them,” says Kelly. “I had a feeling there was some footage of an elephant in a gas mask, but we trawled the internet and couldn’t find it.

“Instead what we started to do was get together the footage we really liked and put it into categories – like footage of airlines and trains. We started to build the themes of the footage and found they built a story.

“We didn’t have to run it in chronological order – we could be more playful with the time scale and jump backwards and forwards in time.”

The script was created separately by Stanley and Worthing-born writer Travis Elborough, while Wiggs worked on the music.

“Music is almost the key to our films – they are reliant on the music for the mood and pacing. It’s what makes them such a pleasure to work on.”

Ian McShane provided the narration on a break from filming Hercules in Budapest, after being approached directly by producer Martin Kelly.

“Once we knew we had him it was great as Bob and Travis could write dialogue with his voice in mind,” says Kelly. “We had a wishlist of narrators for the film which included Ian McShane.

“When his voice came back to our studio in Oxford it was ten times better than we could hope.”

A theme running throughout the film is the post-war birth of the welfare state, and its slow dismantling through the ensuing decades – which was accelerated when Margaret Thatcher came to power.

“It’s left us with a very selfish society,” says Kelly. “People are being driven into the mindset that you have to fight for yourself. London in the film hasn’t changed much – but it has changed rapidly in the last five years.

“Using colour film you don’t feel the distance that you have from black and white. You feel more of an affinity to the people. I look at kids in the film who must be in their 60s or 70s now – who had just a fraction of their lives caught on camera. I wonder what has happened to them since.”

Starts 6.30pm, tickets £11.90. Call 08719 025728.