The plan, according to Bialystock and Bloom, is to stage a flop. Set out to fail in spectacular fashion so that a washed-up Broadway producer and his blanket-carrying dreamer of an accountant can leg it to Brazil with $2 million in oversold production shares. Simple.

That is the synopsis for one of the most celebrated, Tony Award-winning musicals of all time. And that, I think you'll agree, is worthy of a two-hour script. Heck, Mel Brooks originally kept it under 90 minutes on the silver screen, back in 1968. So, what gives, Mel? Why overstretch things with a 165-minute supercut of The Producers on stage?

A loud, overeager and occasionally relentless comedy, The Producers at least has the decency to poke fun at itself and, indeed, the art of musical-making. Everyone involved - including Brooks - is in on the joke, which makes it easier to digest the humour (silly accents, countless and crass innuendos, politically incorrect stereotypes, etc).

It's 'Carry On Broadway', if you will, and with a surprisingly pleasant Jason Manford (Leo Bloom) and a remarkably athletic Cory English (Max Bialystock) in the lead roles. It excels at fully utilising the gap between one song and the next (Brooks' well-oiled punchlines help, of course).

Sometimes, it's a hoot, not least when Leo (the accountant) and Max (the producer in need of a few bob) track down a Nazi playwright (Ross Noble turning it up to 11 as Franz Liebkind), in order to produce their flop ('Springtime for Hitler').

It's aware of its own ridiculousness, and the tunes ain't bad, either. But then, sometimes, The Producers hammers home the joke a lot harder than necessary (between the randy grannies and the disappointing courtroom scene, this show doesn't know what to leave out).

While The Producers is too long, it's also a ballsy, reasonably well-staged spectacle, with an exuberant cast at its centre. And how many other musicals feature an all-singing, all-dancing Hitler, eh?

Running until Saturday HHHII