When it opened in late 2006 at the Menier Chocolate Factory – a mecca for award-winning musical revivals - Little Shop Of Horrors set London’s critical tongues wagging. Nearly three years later and it has finally reached Scotland on the requisite post-success national tour. The polish however, has sadly faded.

First produced in 1982, the musical story of a man-eating plant is based on Roger Corman’s cult 1959 B-movie of the same name. Young Seymour is working at a run-down florist in a dodgy area of town. As the owner, Mr Mushnik, is about to close-down the shop for good, Seymour discovers a venus fly-trap which soon brings them fame and fortune. But he has unwittingly signed a Faustian pact: a fact he swiftly realises as the plant starts to get hungry.

Nuances of plot are definitely not the focus here. The show’s appeal has always been the catchy rhythms of Alan Menken’s fabulously retro score, the comic characterisations and of course the book and lyrics of Howard Ashman. This production, however, is a rather expensive lesson in diction. Vast swathes of Ashman’s hilarious yet precise lyrics are completely lost due to sloppy singing. As luck would have it, on the night I attended we were partially saved by the coincidence of it being a captioned performance. Otherwise, only Keisha Amponsa Banson as Ronette and Clive Rowe as the voice of the plant could be properly understood.

Rowe is so exceptionally talented in fact, that he elicits laughs aplenty even though he is stationed offstage. Elsewhere in the cast, Kraig Thornber is satisfying as the sly Jewish florist Mr Mushnik, though one can’t help but be glad when he’s despatched and the incessant moaning ceases. Clare Buckfield as the love-interest Audrey and Damian Humbley as Seymour are a top-class match with strong voices even if the latter is perhaps physically stretching it as the youthful pushover Seymour.

Alex Ferns – formerly Trevor in Eastenders – has by far the best role: playing the sadistic dentist Orin Scrivello as well as all the other minor characters. Every time he steps on stage, there’s more smut than a boxset of Carry On films. Maybe I’m exaggerating but I’d never quite remembered the sexual implications of the song ‘Dentist’ in which Scivello gyrates with some women and concludes by ordering them to “now spit!” And while we’re on the topic of innuendo, designer David Farley seems to have reinvented the man-eating venus fly-trap as a similarly carnivorous yet disturbingly phallic pitcher plant.

Director Matthew White and the cast have in Farley’s designs the chance to play with one of the most impressive touring sets around. It’s just a shame that a show that looks so great, sounds so mediocre.