It doesn't take much tweaking for The 39 Steps to be played for laughs. In its best-loved incarnation, the 1935 Hitchcock thriller, it brims with enough clipped accents, improbable plot twists, and derring-do action sequences to spawn a whole series of spoofs. Yet the perennial problem of parody remains: if everything can be mocked, does anything on offer count for much?
Not really, is director Maria Aitken's answer, as she and adapter Patrick Barlow give us only four actors, a handful of props and a flash of shadow puppetry to recreate a world of glamorous female secret agents and dastardly threats to national security.
From this, they produce "a minimum of" 150 characters - I lost count - and the recreation of such seminal scenes as Richard Hannay's escape on the Flying Scotsman and escapades on the Forth Bridge.
Although, strictly speaking, Hannay is trying to prevent vital information about air defence from leaving the country, Aitken and Barlow are far happier when he has the chance to get his received pronunciation out for the ladies.
All the chestnuts of am-dram send-up are here: the phones that are picked up before they ring, the extras reluctant to cede their moment in the spotlight. It's amusing enough at first, but this oldhat, one-note take certainly plays to diminishing returns.
Still, Charles Edwards is dream casting as the suave, dashing, hint-of-the-cad Hannay, who soon finds himself the prime suspect in a murder investigation. Catherine McCormack, as the three women on Hannay's journey, starts off with an accent that veers wearisomely between Teutonic and inebriated, but settles down nicely into the icy Madeleine Carroll, stockings-and-handcuffs role. Rupert Degas and Simon Gregor enjoy highjinks with hats, overcoats and packing cases as absolutely everyone else.
Overall, though, it is hard to avoid the feeling that, rather like Hannay himself, this should be in Edinburgh rather than London at the moment. All the fun of the Fringe is here, but die-hard Hitchcock fans are advised to step well clear.
The 39 Steps
Criterion Theatre
Piccadilly, Piccadilly Circus, W1J 0TR
