If you know anything at all about the Leslie Bricusse and Frank Wildhorn musical based on Robert Louis Stephenson’s The Strange Case of Dr Jekyll and Mr Hyde, you’ll know that this is not a light-hearted affair. Through-composed, the score is dark with woodwind and percussion dominating, occasionally atonal and – although there are lyrical moments – for the most part bites deep and in a minor key.

Mark Bailey’s set surrounds the stage with blackened brick walls. Various pieces are flown or truckled on and off to mark scene changes; at the opening performance in Norwich this did not always proceed smoothly, and the amplified sound was variable. Tom de Keyser leads the pit ensemble.

It’s the sort of musical which stands or falls by the main performer, and Marti Pellow thoroughly deserves his ovation at the end. His voice has considerable range, and his acting delineated the research-driven doctor and the blood-lusting creature into which Jekyll’s self-experimenting develops with the simplest of means. Ruffled hair, a change of posture and a swirl of fur-collared cloak are the means.

The two girls contrast nicely. Sarah Earnshaw is Emma, Jekyll’s fiancée. She has a good voice and makes what she can of the somewhat two-dimensional virginal character. Sabrina Carter as Lucy, the street-girl, puts over her cabaret song-and-dance number and her more reflective solos to moving effect. She also acts extremely well, creating a real frisson in the second bedroom scene with Hyde.

Of the large cast, many doubling well-contrasted characters from all levels of society, Jacob Chapman as Lucy’s pimp Spider, Amira Matthews as Lucy’s friend Nellie and David Delve as Emma’s father stand out. Director Martin Connor takes care to remind us how much a contrast there was between Mayfair and St Giles, Harley Street and the East End. Numbers such as “Façade” demonstrate the seepage between these two worlds in one city.