A Scottish film crew working on a multi-million pound production have taken footage of the film hostage in a bizarre dispute over pay.

Psychological thriller Shepherd was being filmed on the Isle of Mull and features award-winning actors Greta Scacchi and Kate Dickie, as well as Victoria star Tom Hughes.

However its release is now in jeopardy after crew members seized the raw footage, or rushes as it is known in the industry, as well as camera equipment on the last day of filming.

Around 50 workers claim they are owed wages by production firm Castle Valley Films, however the company - whose parent firm Golden Crab Film Productions operates out of Pinewood Studios - said it always operates by paying wages in arrears.

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Owner Karim Tshibangu claimed he is effectively being “blackmailed” by the crew, adding that the footage and equipment is worth millions of pounds - considerably more than the workers are owed.

Paul McManus, Scottish negotiator for BECTU, the Broadcasting, Entertainment, Communications and Theatre Union, said: “There are around 50 crew members due two weeks’ wages, so the cameras and the rushes are being kept by the crew until they get their money.

“It’s pretty much unheard of.

“They were promised that all their money would be paid but it wasn’t, so when they finished work on Friday they decided to take the equipment and the rushes.

“We’ve written to the production company to say that we’re happy to agree an exchange so long as everybody gets paid, but we have yet to receive a response.”

Details of the film have been kept tightly under wraps until now and were only due to be announced to industry press this week.

However, The Herald can reveal that the horror centres on a widower who is so overcome by his grief he decides to create a completely new life for himself.

He moves to a remote island and takes up a new job as a shepherd, but when mysterious things start happening to him he is unsure if they are real or imagined due to his grief.

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Mr Tshibangu claimed the production company will pay any outstanding wages to the crew who filmed the movie, but disputed that they were due two weeks’ pay.

He said: “There are only a handful of outstanding payments to be made and we haven’t even finished the project yet, so paying right now is not at all a legal requirement.

“As a result some crew have blackmailed the production team by taking kit and a drive [containing footage] and holding it to ransom until the bills are paid.

“This has made the continued production of this film even more expensive.”

The producer added: “The kit and the drive the crew are holding are worth millions compared to the few thousands that we owe them.

“They were due payment on Friday so it’s just a few days later.

“As with any other production all outstanding money will be paid, whether it’s early, late or on time, it will of course be paid.”

Mr Tshibangu also said that he believed there is a racial element to the issue, claiming there would not have been a problem if he was white.

A Screen Scotland spokeswoman said: “This particular production has not received production funding from Screen Scotland and we therefore have no further comment.

“Screen Scotland supported productions are required to be produced in accordance with the requirements of all unions and guilds having jurisdiction and with all applicable laws and statutes.”

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With scenic and historic locations, Scotland’s Highlands and islands have made for picturesque backdrops in a large number of films and productions over the years.

Other films to be shot on Mull include the 1999 movie Entrapment, starring Sean Connery and Catherine Zeta-Jones, and Kidnapped, an adaptation of the Robert Louis Stevenson book, which starred actor Michael Caine.

In Entrapment, Duart Castle, near Craignure, is used to portray a safe house, while Kidnapped features scenes shot on the beach in Calgary Bay, which is considered to be one of the most picturesque beaches in Scotland.