I just love this show. As one of those self-confessed anoraks who can recite vast chunks of Life of Brian or the Parrot Sketch with all the original vocal inflections, for me Eric Idle’s musical “rip-off” of Monty Python and the Holy Grail is the realisation of a schoolboy fantasy.

It’s got all the silliness you might expect from the team that invented the French Taunter and the Knights of Ni. It’s also got a first-rate book by Idle that cleverly squeezes in other bits of Python to the basic framework of the Holy Grail movie, while adding its own fantastically satirical humour about the musical genre itself.

Plus there are plenty of wonderful songs and music from John du Prez, Idle’s writing partner, who helps to create what is unquestionably a proper musical from the bits of outrageous comedy the Pythons left lying about.

The down side to knowing it inside out and backwards is that when new performers come in and put their own stamp on it, somehow it doesn’t feel quite right. That’s not to say the show doesn’t stand up entirely in its own right – it undoubtedly does, with bells on – but there is just a bit of a nagging voice murmuring quietly in one’s ear: That’s not how John Cleese did it…

That said, this touring production, directed by Christopher Luscombe, brings the house down. Python fans in the audience chuckle knowingly from start to finish, while anyone who’s lived on another planet for the past 40 years and therefore might not actually know every line can find endless sources of belly-laugh gags, both verbal and visual.

It’s become customary with Spamalot to parachute in star names – as the show self-referentially parodies – in the roles of King Arthur and the Lady of the Lake. In Northampton, we get stand-up comedian Marcus Brigstocke, who battles manfully if a little uncomfortably with the singing and dancing he’s required to do, and Emmerdale’s Hayley Tamaddon, whose over-the-top diva gets some of the biggest laughs.

But the stand-out performance comes from one-time EastEnder Todd Carty as Arthur’s downtrodden servant Patsy, banging his coconuts together for horses’ hooves and giving a fine rendition of the infectiously catchy Always Look on the Bright Side of Life. You’re whistling already, aren’t you?

It’s colourful in a pantomime kind of way and guaranteed to send you home with a smile and a whistle. And what more could you ask of a musical?

- Michael Davies