The plot of the 1992 comedy Sister Act – a smash for Whoopi Goldberg after Bette Midler turned it down – could be scratched on a sacramental wafer. Having witnessed a murder, the brassy, small-time singer Deloris Van Cartier hides out in a convent where she transforms the nuns’ lives with music. Over-extended for the stage, the show contains few of the miracles required to feed the multitudes, though pluses include the colourful late-1970s, south Philadelphia setting and a cast headed by a full-throated, comically twitchy Beverley Knight (stepping in for Goldberg, who was set to reprise her screen role before the pandemic struck). Jennifer Saunders is the main draw, bridling and bristling as Mother Superior. To the sinful Deloris’s enquiry about whether the convent has a smoking section, she responds with prim, evangelical certainty: “Yes, my dear, and you’re heading for it.” There is nothing funnier here than the moment when Saunders, slumped in her chair as she anticipates the latest bout of choral caterwauling, is startled by the sisters’ new-found tunefulness. Eyes darting frantically around the room to locate the origin of these heavenly harmonies, she yanks open the fabric of her coif to give her ears a better shot at hearing. The director Bill Buckhurst, who famously staged Sweeney Todd in a real pie shop, marshals a sprawling cast which includes Lizzie Bea as Sister Mary Robert, singing hungrily of the pleasures denied to her, such as surfing and skinny-dipping. Indeed, it’s one of the show’s quirks that few of the nuns seem suited to a life of austerity; even Mother Superior swigs from a hip flask. Inspiration flags before a finale in which Morgan Large’s mock stained-glass set glows rainbow-coloured, but good humour sees it through. One exception is the big femicide number crooned by Deloris’s pursuer Curtis (Jeremy Secomb) as he and his soulful backing singers debate whether to stab, shoot or drown their quarry, or to “give her skull a big dent / With a blunt instrument.” This is one occasion when the composers Alan Menken (music) and Glenn Slater (lyrics) should have taken a vow of silence.