Dan Clarkson and Jeff Turner’s irreverent, unauthorised JK Rowling parody is becoming as much of a Christmas fixture as reindeers and indigestion. But this year’s revival — threatened to be the last — might have to magic up some new fans. The original audience probably now prefers Special Brew to Sirius Black, fags to Hagrid.

This breathless bolt through the bullet points of seven Potter books in 70 minutes is aimed primarily at kids but adults who yearn for the bad plays of Crackerjack or have yet to shake off their inner idiot may find plenty to enjoy, too.

Grown-up gags and well-polished asides help things slip down nicely. Jeff is a decent squeaky-clean Harry, while hard-working Dan is equal parts entertaining and irritating as everyone else.

What this lacks in emotional depth it makes up for in shallow but riotous puerility. Highlights include a chocolate log smeared on Dan’s face and an audience-participation Quidditch game.

The stand-out moment by far, though, is the finale, which features Dan as Voldemort, customising the lyrics of I Will Survive. If the duo return next year — though, as new CBBC hosts, this really may be their swansong — a singalong rewrite would be spellbinding. Anyone for Potted Potter The Musical?
Until 3 January (0870 060 6632, www.theambassadors.com/trafalgarstudios).