Now why on earth didn’t the talking heads on the TV news have the gumption to use an oompah band to explain the fearsome complexities of the banking crash? It’s an interesting question, but the simple answer could be that an oompah band doesn’t really tell you anything about high finance or toxic debt.

A hit in Edinburgh this summer, Dunstan Kornicki and Charlie Talbot’s show would be likeable enough as a short skit. The idea that it is worth 70 minutes of anyone’s time is mystifying. Even more baffling is that the production team persuaded the economics editor of a major national newspaper to write a foreword for the programme. We can only hope that he knows more about share prices than he does about musicals.

Not that Blow Up! is a musical in any case. What you get is a stale comic monologue about City life narrated by Talbot in a cod-German accent as he explains how his dimwitted alter-ego, Max Klein, came to play a supporting role in the great confidence trick surrounding derivatives and sub-prime mortgages. The level of humour becomes apparent at the beginning as he reminds us that there is a much-used word that rhymes with “banker”.

Every time he reaches for another limp pun or punch line, Klein briefly gives way to the five musicians of Oompah Brass. Their quicksilver arrangements of an assortment of pop songs ranging from the Bee Gees’ Tragedy to Michael Jackson’s Don’t Stop ’til You Get Enough possess the energy and epigrammatic wit that are sorely missing from the script itself.

With luck the band will get the corporate gigs that they are touting for in the programme. The rest of the evening — directed by Talbot’s father, Philip — is merely tedious. Do we learn anything that we couldn’t have gleaned from a 60-second piece to camera by Robert Peston? No. Does Talbot give us an amusing Teutonic stereotype? Nein. Even the kind of City narcissists who went along to the Royal Court to see themselves mocked in Caryl Churchill’s Serious Money are unlikely to have much fun laughing at jokes that would never get past even Bruce Forsyth’s quality controller.

As you trudge towards the exit you cannot help falling prey to the depressing thought that Edinburgh critics are the media equivalent of those dodgy ratings agencies that landed the banks in trouble in the first place. In this business, all you need is hype, an audience that is ready to be duped and some even more gullible journalists desperate to unearth the next big thing.

Box office: 0844 2090326, to Nov 26

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