No, I didn’t know that Beowulf was a panto story either. It may well be the first time that this Anglo-Saxon epic poem of uncertain authorship with a mythical Danish setting been adapted in this way, and seems rather fitting as Charles Court Opera’s cult ‘boutique’ pantos at the Rosemary Branch tend to have something of the avant-garde about them. It’s a panto with gravitas (is a pantomime a kind of mock heroic narrative? – discuss!), free from celebrity gimmicks and performed by classically trained singers who also have plenty of experience as comic actors. While the characters’ clunky names might be unfamiliar, their re-casting as recognisable panto stock figures is neatly done, offering a Christmas treat that is comfortingly cosy and a little bit different.

Something is rotten in the state of Denmark: King Hrothgar (Simon Masterton-Smith) is an alcoholic addicted to partying and is ‘Holding Out For a Hero’ to slay Grendel, the beast who has been stealing courtiers to feed to the dragon that he and his mother have been keeping under control for centuries. To save the day, in strides the comically macho and camp Beowulf (Kevin Kyle), a redoubtable warrior clad in a leather skirt, with a South London accent and no idea of how to chat up girls. In tow is his faithful sidekick Wiglaf (a hearty Amy J Payne – the boys shouldn’t get all of the fun of cross-dressing) and it seems something of a pity to break up their ‘bromance’. Perhaps best of all is Philip Lee’s one-armed Grendel, not quite the fearsome monster of lore, who has a unique falsetto, a phobia of sheep and might look like a walking pustule but is really rather sweet (a gang of Grendel groupies were very vocal in their appreciation). Director John Savournin plays his mum (the role played by the far less radiant Angelina Jolie in the 2007 film) with blowsiness and touching insecurity.

As befits an opera company, the music isn’t standard panto bubblegum. I don’t want to reveal too much as much of the delight comes from the surprise, but well-known musical theatre numbers have a very different effect when taken out of their usual context and I relished the ingenious Sondheim pastiches. I have no idea how many audience members ‘get’ it, but Sondheim’s rhythms are so effective for storytelling that it shouldn’t feel like an elitist in-joke. All the cast are talented singers, but the dramatic soprano of leading lady Catrine Kirkman takes top vocal honours. Her Princess Hrothmund has something of Maria Callas’s Tosca about her, but fortunately gets a happier ending than throwing herself into a ravine. James Perkins’s wooden set is suitably snug and the Eaton-Young Piano Duo provide lively accompaniment and fun comic cameos.

How faithful is it to the original poem? I couldn’t say, as I’ve never read it. For more scholarly silliness in which high and low culture hilariously collide, Sir Gawain and the Green Knight – the panto next year, perhaps?

Beowulf – the Panto plays at the Rosemary Branch Theatre until 8 January 2012. For more information and tickets, please visit the website.