Although it can derail the lives of those affected by it, Tourette syndrome is seldom taken as seriously as it deserves, not least due to the sometimes sweary nature of sufferers’ involuntary outbursts. A biopic of prominent Tourette’s campaigner John Davidson, I Swear combines an earnest interrogation of this neurodevelopmental disorder with amusing episodes, and benefits from a barnstorming turn from Robert Aramayo in the lead.

Set against the unglamorous backdrop of suburban Galashiels, and kicking off in 1983, the film introduces a young John (superbly played by Scott Ellis Watson) as a confident, capable lad making the transition from primary to secondary school with ease. When John’s tics start up, in a time before Tourette’s was known and understood, it’s assumed he’s merely ‘acting the fool’, effectively exploding his academic and footballing prospects and his parents’ relationship, when his father walks out. Shirley Henderson plays John’s stiflingly negative, martyr-like mother, while Maxine Peake is the mum of a friend, who becomes John’s rock, and Peter Mullan is his kindly employer. With Aramayo taking over as the adult John, the film recreates his inevitable brushes with the law, before his re-invention as a trailblazing champion of the Tourette’s cause.

Writer-director Kirk Jones (Waking Ned, Nanny McPhee) helms competently if anonymously, while the film is structured in a somewhat formulaic fashion with a sentimental score and predictable musical choices. However, the script is compassionate, wise and witty and the performances are exceptional. Best known for his small screen work (including The Lord Of The Rings: The Rings Of Power), Aramayo embodies Davidson to a quite astonishing degree, with his tics seemingly emerging from a place deep within. I Swear is a tremendously moving tale of overcoming adversity that’ll break your heart before piecing it right back together again.

I Swear is in cinemas from Friday 10 October.