Spamalot was always an inane musical extravaganza, or the best ever medieval pantomime, depending on your satirical mind-set, and it's decisively the latter in this slick and pretty scaled-down version directed by Christopher Luscombe and smartly designed - in classic panto style - by Hugh Durrant.

The original Broadway production by Mike Nichols, "lovingly ripped off from Monty Python and the Holy Grail," cost $11m and opened seven years ago to an advance of twice that amount.

One assumes it's been a milk cow ever since, with Simon Russell Beale replacing Tim Curry as King Arthur in the West End and this touring version playing recently at the Harold Pinter with Marcus Brigstocke in the lead.

Now Stephen Tompkinson takes the reins for the holiday season, hotly pursued by a delightfully clownish Todd Carty as his ragbag valet, clicking his coconut shells together, as Anna-Jane Casey lets rip as the Lady of the Lake, treating us to "The Song That Goes Like This" before lamenting her rarity value in the second act - "Whatever Happened to My Part?"

Actually, the one thing Luscombe's well-drilled production resoundingly reasserts is the origins of Monty Python in Footlights revue. Many of the scenes play like front cloth sketches, and there are new topical gags about Boris Johnson, Susan Boyle, Peter Hall (the last thing Tompkinson needs, he says, is a heckle from that source) and the ruckus in Downing Street now known as "pleb-gate".

Tompkinson, currently starring on television in DCI Banks, has always been a fine stage actor we don't see too often, and his Arthur is notable for its comic deftness and deceptive modesty; there's no attempt to slaughter us with gagging. The over-the-top face-pulling is left to the chain-mailed French Taunter ("I fart in your general direction") and the single, sad representative of the knights who say "Ni".

All the favourites are in place: the limb-lopping duel, the killer rabbit, the pile of dancing corpses, the surprise outing to a cabaret night in Las Vegas (just two show girls in this version) and the opening red herring, or "Fisch Schlapping Song," when the weather man’s directions to England are misheard as Finland.

It never worked here, but I really miss the outrageous ensemble show-stopper (originally led by David Hyde Pierce) about the necessity of having Jews on Broadway, and the cod romantic narrative with Prince Herbert remains a problem (not funny enough).

But the "Find Your Grail" number more than compensates, and the great joy of the show – book and lyrics by Eric Idle, who has displaced John Cleese as the Voice of God, and music by John Du Prez and Idle – is its affectionate send-up of musicals as gloriously silly pageants with no greater purpose than sheer entertainment. All together now, "Always Look On the Bright Side of Life…"