If only Jimmy Carr hadn't done that Barclays bank sketch.

Although he'd never been a particularly political comedian, Jimmy Carr's role as a 10 O'Clock Live presenter moved him - whether he liked it or not, and presumably he did - into the realm of satire.

And it was a pretty canny move, too. Carr is smart, and brilliantly quick, and often served as an interesting, opposing view during the presenters' round-table discussions.

But if only he hadn't done that Barclays bank sketch.

Or to put it another way: if only he hadn't employed people to help him reduce his tax bill to around 1% of his income. Because this is, of course, what he was criticising in the aforementioned sketch.

If there's one thing we demand of our satirists, it's a feeling that they are telling us the truth. That they are shedding light on an issue we hadn't noticed or quite grasped before, or couldn't explain as pointedly, viciously or as succinctly as them - and that in lampooning such things, they themselves are (rightly) taking the moral ground. And such a trade between us and the satirist requires trust.

It's why people still listen to Wagner's operas despite his anti-Semitic views (younger readers: swap 'Jacko' for Wagner and 'dodgy children sleepovers' for anti-Semitic views). It's why I don't give a flying fig about Woody Allen running off with his stepdaughter, as long as he still makes me laugh (good save with Midnight In Paris, Woody). It's why the Tories got away with their espousal of 'family values' in the '90s - until many of them were exposed as lacking such values.

In short: most of us don't care what public figures get up to if it doesn't affect our view of their 'product'. But as soon as it does - if you're a politician and your product is your policies or you're a satirical comedian and your product is your routine - then you run the risk of being accused of hypocrisy. And if anything blunts satire's weapon, it's being accused of the exact same thing you're lampooning. Whether that's idiocy, hypocrisy or tax avoidance.

From Juvenal to South Park, via Voltaire, George Orwell and Monty Python, our satirists have never needed to be squeaky clean to be effective - they've just needed to imbue that sense of truth and trust. As I say, it's a trade. When I read Private Eye, or watch Jon Stewart or Stephen Colbert, I don't expect these Purveyors Of Truth Via Satire to be perfect. But I do hope - or indeed, perhaps naively take it for granted - that Stewart, Colbert and the Eye staff are exposing something that they themselves find abhorrent or ridiculous, and as such aren't engaging in it themselves.

It's why the mud doesn't really stick on Armando Iannucci for his acceptance of an OBE this week. Alastair Campbell and others accused him of hypocrisy for becoming a part of the Establishment he lampoons; yet a) to my knowledge, Iannucci has never spoken out against the honours system, and b) Campbell himself is part of this 'Establishment' but disapproves of the honours system. An entirely honourable (if you pardon the pun) position to take - yet a degree of nuance that he doesn't afford Iannucci, despite Iannucci making it clear on receiving his honour that he doesn't intend to stop lampooning anyone.

And when it comes to the moral side of such things, nuance is key, of course. Is accepting an honour an endorsement of an archaic, unjust system, or the acceptance of recognition for your work? Is Jimmy Carr behaving immorally by avoiding taxes, or simply being canny and frankly it's none of our beeswax? These are legitimate questions that could be argued 'til the cows come home. Especially if you're drunk. And live on a dairy farm.

But for now, I'll return to my original point. If only Jimmy Carr hadn't done that Barclays bank sketch.

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