It’s an interesting notion – taking a well-known and much beloved tale, isolating a minor character and then exploring their backstory. Such is the case with Birmingham Rep’s I Was A Rat!, which takes as its protagonist one of the rodents that was wonderfully transformed into a footman to whisk Cinderella off to her magical Ball.

But what happens when the fairy dust settles? What about those left behind? In the case of the rat-boy who wandered off and missed being changed back to his original form, he stumbles across an elderly couple (Tyrone Huggins and Lorna Gayle) who adopt him and give him the unlikely – for an erstwhile rat anyway – moniker of Roger.

But life in the world of Man isn’t easy for someone whose idea of a good time is gnawing on anything that doesn’t have a pulse. Roger faces suspicion and cruelty from everyone he meets thereafter and, inevitably, his life as a boy begins to crumble around him. Officials, doctors and educators want nothing to do with him and he seems doomed to a life of being "The Rat-Boy" in the awful Mr Tapscrew's (Christopher Dingli) travelling show.

As Roger, former Billy Elliot star Fox Jackson-Keen  excels, offering an extraordinarily adept performance of physicality and innocent clarity. At only 17 years of age, Jackson-Keen exudes a confidence far exceeding his years and provides a fulcrum for the myriad other characters who move frenetically through Roger’s life.

As his parents, Huggins and Gayle are a wonderfully ebullient double-act of homespun philosophy and rock-solid values that works as an anchor to the real world during the more fantastic sequences.

Teresa Ludovico’s adaptation of Philip Pullman’s novel is a vivid and thoroughly engaging piece of work for all ages, although the very young might find the freak-show’s sinister clowns a little overwhelming. Ludovico keeps her eight-strong cast on their toes, producing a slick and mesmerising vista of colour and surreal characters.

The stark black-box set catapults Luigi Spezzacatene's rich costume palette with a powerful contrast and, although Vincent Longuemare's no-frills lighting isn't always quite as successful, when it does work, it's striking and evocative.

A not-to-be-missed departure from the norm and an ideal way to introduce young people to the theatre-going habit.