THERE’S a lot riding on the new Mary Queen of Scots movie, it seems, what with First Minister Nicola Sturgeon saying it will help showcase Scotland as a “world-class location” for film and TV productions while culture secretary Fiona Hyslop reckons it offers a “great opportunity” for promoting tourism in the country. And who can blame them - at a time when our economic future is looking decidedly uncertain, it’s nice to think that we can all be saved by the sprinkling of some celluloid stardust.

There’s just one thing: having been produced by a coalition of American, English and Chinese companies the film isn’t really Scottish at all. Sure, it features hills, glens and, with David Tennant playing protestant reformer John Knox and Martin Compston in the role of Mary’s controversial third husband the Earl of Bothwell, some of our finest actors. But with the titular role being filled by Irish actress Saoirse Ronan, is it really credible to suppose the film can have any impact on our future if it can’t even provide an authentic reflection of our past? Worse still, has it deprived one of our home-grown actresses the opportunity to portray one of our best-known historical figures?

The argument for authenticity in casting is one that continues to rage, particularly when star names are seen to be taking roles that could be better filled by lesser-known minority actors. Yet as Bryan Cranston said when defending his decision to play a quadriplegic in comedy drama The Upside, as the job of an actor is by definition to portray someone they are not, it makes sense for casting decisions to take account of who is likely to attract the biggest audience rather than whose life most closely matches that of the character. After Cranston won global acclaim for his portrayal of chemistry teacher turned criminal mastermind Walter White in hit TV show Breaking Bad, it simply made good business sense for The Upside director Neil Burger to cast him in his film. The business-case argument is certainly a sound one and, as the casting of American Andie MacDowell in quintessentially English film Four Weddings and Funeral showed, giving a film the potential to attract a much wider audience can have a knock-on positive effect for film-making more generally.

Read more: Mary Queen of Scots film review

But of course the arguments to the contrary are sound too. When Cranston was initially cast in The Upside, US disabled-rights group The Ruderman Family Foundation, which had earlier objected to the casting of Alec Baldwin as a visually impaired man in Blind, slammed the move as discriminatory. “Casting a non-disabled actor to play a character with a disability is highly problematic and deprives performers with disabilities the chance to work and gain exposure,” its president, Jay Ruderman, was quoted as saying at the time.

Such attitudes are leading to change, with Holywood actress Scarlett Johanssen last year pulling out of playing transgender male Dante ‘Tex’ Gill after a backlash from trans actors and queer activists. Similarly, the straight actor Darren Criss, who played gay characters Blaine Anderson in Glee and Andrew Cunanan in The Assassination of Gianni Versace: American Crime Story, vowed never to take such a part again for fear of becoming “another straight boy taking a gay man’s role”.

A logical extension of that would be that those from minority groups should also be excluded from playing non-minority roles, but the recent experience of Surrey-based Grange Park Opera shows the danger inherent in that argument. Having committed to staging George Gershwin’s Porgy and Bess in the summer, the company has run into casting difficulties because it has been unable to find enough singers for it to meet the legal requirement of having an all-black cast. Though Gershwin wrote the opera in the 1930s as a vehicle for black performers, the implication of Grange Park’s experience is clear: with too few roles explicitly written for people from their background and there still not being enough opportunities for them to fill roles that are not race-specific, black people have made the self-fulfilling decision that the opera world is not for them.

These are all issues that Mary Queen of Scots director Josie Rourke, whose background is as artistic director of boundary-pushing London theatre the Donmar Warehouse, is clearly well aware of. Though she has all but ensured the film’s commercial success by casting Hollywood favourite Ronan as Mary alongside Australian stars Margot Robbie and Guy Pearce as Queen Elizabeth I and William Cecil, she is also promoting diversity by casting ethnic-minority actors Gemma Chan, Adrian Derrick-Palmer and Ismael Cruz-Cordova in what would undoubtedly have been white roles.

As Ms Rourke herself says, when it comes to acting everyone’s just pretending anyway, so it really is no big deal that Mary isn’t being played by a Scottish actress. And if her telling of Mary’s story attracts audiences to Scotland and our economy gets a boost in the process, then so much the better.

Read more: Mary Queen of Scots film review