Sporting documentaries are often very hit and miss, with an interest in the subject often a prerequisite to enjoyment. However, great documentaries traverse those kind of boundaries. Notable entrants into the milieu include Touching The Void, Senna, Riding Giants, When We Were Kings and Hoop Dreams. In Louise Osmond’s Dark Horse she concentrates on a perennial favourite of audiences: The underdog.

In a small mining village in Wales a dream begins to take life when a barmaid decides to breed a thoroughbred race horse. Jane forms a syndicate of 30 with regulars of the working men’s club, and eventually Dream Alliance is born. After he works his way through Philip Hobb’s stable, Dark Alliance makes his debut and is soon a surprising hit. As the working class collective rub shoulders with the the rich and entitled, they start to believe that their dream could come true – to win the Grand National.

Dark Horse is a real underdog story, both in terms of the pedigree of the horse himself and also the characters in the syndicate. And they certainly are characters. It’s a slight story in many ways, and with the choice to re-enact certain moments, it does feel very low key. However, Dream Alliance was much more than a horse. He encapsulated the hopes and dreams of those living in a poor mining area, and brightened up all their lives. Whilst the background is only really touched-on, the only questionable note was the decision to keep running him, despite an injury.

Dark Horse is out in cinemas on Friday.