Stephen Beresford says Facebook played a central part in making 'Pride'.

The film, which stars Bill Nighy and 'Sherlock' actor Andrew Scott and centres on the Lesbians and Gays Support the Miners campaign, dates back 30 years - which posed some logistical problems when it came to conducting research.

Reflecting on the new flick - which is based on a true story - Beresford explained at the London premiere: ''I had to track down [the real-life characters], which wasn't easy because everything they did was pre-internet. So I had to track them down using more traditional means.

''But, in the end, I did track them down using the internet, because the group had made a video of themselves. At the end of the film there was a 'Thanks to...' credit. I looked them up on Facebook, knowing these guys would be in their 50s and 60s.

''There was one name [that was really distinctive], and I thought, 'There can't be two people with that name.' And there wasn't.

''He was the first one I met. I wrote a little email and asked if he was involved in the Lesbians and Gays Support the Miners campaign. He wrote back and said, 'No-one has asked me that question in 30 years.'''

'Pride' opens in UK cinemas on September 12.