Directed by Jonathan English. Starring James Purefoy, Paul Giamatti, Kate Mara, Brian Cox, Mackenzie Crook, Jason Flemyng, Derek Jacobi, Charles Dance 16 cert, gen release, 120 min

THERE JUST aren’t enough films these days featuring medieval warriors covered in cow dung. If this writer had his way, no week would pass without some warty peasant having his arm severed by a rusty broadsword.

So there are reasons to welcome Ironclad. A rough blend of Zuluand the Black Knight sequence from Monty Python and the Holy Grail, this economically budgeted British film is not short on medieval gore. Barely a moment goes by without some unfortunate warrior getting an unwelcome glance at sections of his innards. Sadly, Ironclad is also more than a little overstretched and underwritten. One can't honestly muster any surprise at the news that, shot back in 2009, it has been lying on the shelf for a spell.

Mixing up its genres to dizzying effect, Ironcladbegins with Brian Cox, one of the earls who forced King John (Paul Giamatti) to sign Magna Carta, touring brothels and dungeons to assemble a crack team of operatives. One is a safe cracker. Another is the dynamite man. A third knows how to bypass burglar alarms. We're making that up, but the opening does recall that of a "bunch-of-guys" heist movie.

Lord Cox’s real aim is to secure Rochester Castle from the attentions of King John’s regrouping counter-revolutionary forces. If they can hold off until the French arrive, then the innovations in Magna Carta should be secure. (Yes, you read that right. This is a British film in which invading Frenchmen are the good guys.)

Unfortunately, the eventual defending force comprises only a little over 20 men. While King John musters his thousands and tightens the bolts on his catapults, the crack force grimly contemplates its unlikely mission. You can see what we're up to with the Zulucomparisons.

The performances are all up to scratch. The endlessly reliable Giamatti makes a weedy spoilt child of King John. James Purefoy, Mackenzie Crook and Jason Flemyng confirm that geezer- culture flourished centuries before Guy Ritchie first drew breath. But, after establishing its core scenario, the picture fast becomes a gruelling compilation of repetitive forays.

If it makes more than five bent florins at the box-office I’ll eat my own scabbard.