Sold out performances of John Kander and Fred Ebb's Cabaret at Cheltenham's Everyman theatre this week provide more evidence, if further were needed, of the widening spread of celebrity culture.

Many people are surely there for the merits of the show itself — one of the truly great musicals, along with (for instance) West Side Story, Kiss Me Kate and Oklahoma! — and others for the chance to see the long-shining star Wayne Sleep as Emcee. But it was clear from the reaction of the first-night house that just as many are out to cop a view of Samantha Barks, a runner-up in BBC1’s recent I'd Do Anything talent show, in her professional debut, eager to find if she could hack it in the role of Sally Bowles.

The sad truth, I am afraid, is that she cannot. Her performance is amateurish, not to say at times almost embarrassingly bad. True, she has a powerful singing voice — if no adequate means to rein it in for artistic effect — but the acting skills so necessary in this subtly nuanced part, in which the spoken word is as important as the songs, are nowhere to be seen. A pity, when others — including Sally's boy Cliff (Henry Luxemburg) and their elderly pals Fraulein Schnneider (Jenny Logan) and Herr Schultz (Matt Zimmerman) — are portrayed so well. Cliff, properly, is given a stronger-than-usual backstory of homosexuality; the boyfriend (Hendrick January) who continues to vie with Sally for his favours is seen being given a vicious beating up by Nazi thugs before being daubed with the pink triangle, National Socialism's badge of homophobic hatred.

Samantha's deficiencies, it has to be said, seemed not to be noticed by many of those in the stalls around me. For them the plucky girl had pulled it off. This was the story of the night — and woe betide anyone who chose to recognise another, as I discovered during the interval when I dared to raise a voice of dissent at the bar.

Fortunately, this fine revival, first seen in the West End two years ago, still offers much to enjoy (or endure), including an arresting, even frightening, performance by Wayne Sleep. His camp grotesqueries tellingly reflect the rotten, anything-goes culture of 1930s Berlin in which the Nazi ideas took root.

Under director Rufus Norris the dark heart to Joe Masteroff's book (after Christopher Isherwood) is presented more powerfully than I have ever seen it before. While we laugh early in the evening at the sight of tart Fraulein Kost's (Suanne Braun) well-built "nephew from Hamburg" (ho, ho!) striding starkers from her bedroom, nudity is used later to an altogether different effect.

A writhing heap of humanity, naked beneath the 'showers' in an extermination camp, is the ghastly image on which the show ends. Small wonder that none felt able to applaud until some time after the curtain had fallen, and then rather guiltily.