Alas, there is a problem when you make a movie about real historical events and do it by telling a fictional story. Some films can overcome it – Suffragette for example used Carey Mulligan’s fictional character as a cipher for the combined story of many women of the time. Her character in that film is present at, but not the central figure in, the real historical events. And that’s the important dividing factor here. What Stonewall does, unforgivably in many eyes, is invent a character and make him lead the events of the story. The fact that the fictional character invented for the film is CIS male and white, and is seen leading and throwing the first rock of the riots caused even more controversy – particularly as the leader of the riots in real life was widely credited to be a transgender woman of colour Marsha P Johnson (Otoja Abit).

The film is about the 1969 Stonewall riots which happened outside the Stonewall Inn, Greenwich Village, New York. It was an uprising against a police raid at a bar which welcomed openly gay customers. It was the riot which kick-started the gay liberation movement in New York, and the anniversary march to commemorate it was the first Pride march. It is also inspired the name of the UK LGBT organisation Stonewall in 1989. It is a seminal moment in the changing attitudes of the world towards homosexuality and is an incredibly important moment in the centre of the movement. If you’re going to make a pro-LGBT rights movie about it, you have to be wary of that and just how important it is seen.

We are introduced to the gay scene of late 60s New York through the fictional eyes of Danny Winters (Jeremy Irvine), a young college student from the mid-west. His backstory, of being thrown out of home by outraged parents, is a familiar one and well told. Jeremy Irvine is a good actor, and he plays the corn-fed kid from the sticks coming to the big city well. He meets many LGBT characters who apparently have their stories taken from many people. Other characters are either real like Frank Kameny (Arthur Holden) and Ed Murphy (Ron Perlman) or hinted at. Jonny Beauchamp performs well as Ray, who remains without a surname despite being heavily drawn from a real person. The character of Trevor, played with slightly more than his usual bland aplomb by Jonathan Rhys Meyers, is clearly signposted as someone who existed but is similarly never fully named. Perhaps because the character behaves so badly in the film.

On one level it does make sense narratively for there to be an outsider character we can watch, who makes their way to be inducted into a world of which the audience watching might not be aware. But, and it is a big but when dealing with history, it needs to be true to and in the spirit of what actually happened otherwise what’s the point? The major criticism against the film is that it takes an important instigating event and both whitewashes it and makes its central figure CIS male. But if it’s also conflating all but a handful of named individuals why tell a specific historical story?

As a movie, in many ways, it does a perfectly serviceable job – the creation of the world of 1960s New York is very nicely handled. Design, lighting, set, costume all cracking. The performances are good on the whole too. It’s a little patchy and drawn out, but sympathetic in its telling. From a 21st century perspective there is still a huge amount of work to be done, but the idea that less than 50 years ago attitudes towards homosexuality were so hideous in mainstream life, both legally and politically is still horrifying to watch. The scenarios come across well. The dialogue is not bad. The direction and pacing are good. Roland Emmerich shows he is capable of handling intimate drama as well as bringing the world to an end. And as an audience it cannot be denied that the film is a positive and wholly sympathetic championing of gay rights.

The ridiculous misstep the film makes is to not just focus on the actual people it actually happened to.

I enjoyed the movie while I was watching it, and was keen to know more about the complete story afterwards. I felt cheated, as it was only then I discovered the fact that the lead character I had been following throughout the film didn’t actually exist. The character who on screen is the driving instigator of the riots was never there. And many of the other characters who are shown are composites. Should somebody know the history before seeing a movie? It’s a tricky one. Suffragette proved it is possible to tell a fictional story within a historical context and for it to remain true to the spirit and reality of the history. Is saying “it’s only a movie” enough to paper over the cracks?

For me it made a fairly ordinary but entertaining 3ish star movie become something else, something much less. It was a huge shame it couldn’t have been more truthful, because from the evidence presented here Emmerich and screenwriter Jon Robin Baitz should’ve been able to handle it fine.

Stonewall is out on DVD on Monday 1st August.