There are few delights in comedy keener than listening to Ronnie Corbett tell a shaggy dog story. For that alone, Sandi Toksvig's Christmas Cracker is worth a tug. Its second half includes 10 winning minutes of solo Corbett; comedy's pocket dynamo also stumbles through Christmases past, present and future in a shambolic Dickens retread. But Little Ron's contribution is one among too many. Talk about shaggy dogs: this show has the coiffeur of a particularly hirsute Afghan hound. It needs a trim and a tidy.
It's essentially an evening of variety. West End chanteuse Maria Friedman sings Winter Wonderland. Five Guys Named Moe strut their harmonising stuff with a precision absent elsewhere; conductor Charles Hazlewood marshals the audience in a "ding-dong" sing-song. Between acts, a backstage story unfolds in which Toksvig's stage manager falls for a fairy, who in turn falls foul of some black magic. As the mouthy fairy, Petra Massey of the theatre company Spymonkey steals the show, embodying demonic possession with gleefully un-Christmassy malevolence.
But all this wing-and-a-prayer dottiness frays the patience in act two, as Toksvig manhandles a guest-star through the Scrooge role in A Christmas Carol. With its irreverent gags and compromised celebs (on press night: Green Wing's Stephen Mangan), it wants to be a Morecambe and Wise-style spoof. But it's slapdash and barely funny enough to excuse the ruination wreaked on a great story. (Children may be nonplussed.) Corbett duly comes to the rescue, a fireside joke-teller with a star of Bethlehem-sized twinkle in his eye, and the show's uncynical good cheer just about propels it into its fourth hour. But – as Toksvig and Corbett shouldn't need telling – smaller might have been more beautiful.
