It was just a photograph: a terraced house with three Union Flags on it, a white van parked outside and the simple caption "image from #Rochester". But it was enough to secure Emily Thornberry's fate, and the claim from one of his aides that Ed Miliband had "never been so angry".
We can question Miliband's rage (is that really what makes him most angry? Not the daily atrocities of Boko Haram? Not the growing number of suicides directly related to benefits cuts? Not the fact that every FTSE CEO earned more than the average annual salary by the end of the first week in January?) which makes him seem more than ever like a Playmobil prime minister. But Thornberry's crime was clear, even if her actual tweet wasn't: she had been caught looking down on a voter, and that is politically unacceptable.
Thornberry, of course, was not alone in this last year. We're perhaps more conditioned to expect snobbish attitudes from a Conservative politician but Andrew Mitchell still lost his job over Plebgate, and David Mellor's character turned out to be even less appealing than his face. And that's before we even start on Ukip and their ever more grisly list of candidates, who seem ever more like a game of Guess Who: Bigots Edition?
What all these stories showed us is that despite years of efforts to the contrary, Britain is still a divided kingdom: one where social mobility is actually declining, where the richest 1% have more wealth than the bottom 55%, and where, with tuition fees of £9,000 - that's more than £1 for every hour of the year - many of our brightest children are deterred from attending university.
But we still find it hard to discuss social class. It can feel like a conversational minefield, sown with the potential for disaster: there are so many subtleties of language, identity and heritage that it can feel perilous just to raise the subject. And that's where comedy comes in. Social class has been a staple of British comedy ever since Chaucer: there are jokes about it in Shakespeare, Thackeray and Austen, just as there are more recently in the work of Alan Bennett, Alan Ayckbourn, Alan Bleasdale, Alan Plater and several writers not called Alan. Social class - and its inevitable accompaniment, social embarrassment - is the backbone of British sitcom, from Fawlty Towers and Rising Damp to Keeping Up Appearances and Blackadder, as well as being at the heart of popular British theatre.
But it's in the cinema that social class comedy became more than a reliable source of jokes and closer to being a portrait of Britain itself. Class division has been a theme of British comedy cinema right from its very beginnings in the late 1890s, when film-makers like George Smith and Walter Booth produced short films, often inspired by music hall routines, that mocked the authority figures of the day, and introduced stock characters like the pompous policeman and flirtatious maid.
In the early part of the twentieth century this was developed by film-makers like Chaplin - in his British films - before reaching a remarkable high point in the Ealing comedies of the 1940s and 50s, which are too easily dismissed as cosy. Watch Kind Hearts And Coronets, The Man In The White Suit or Passport To Pimlico and you'll see a sharp satirical intelligence beneath the witty dialogue and good manners: these are films that celebrate the best of Britain while being fiercely aware of its undersides of snobbery, cruelty and inherited privilege, particularly those directed by the great Alexander Mackendrick.
A year on from Benefits Street, and just three months before the most contentious election in decades, this year's LOCO London Comedy Film Festival is joining the social class debate by screening a season of social class comedies including the Ealing comedies mentioned above as well as more recent films including Gosford Park, Life Is Sweet and Shane Meadows' Somers Town. We're also bringing the conversation right up to date with a unique Social Class gameshow, with panellists including award-winning novelist A.L. Kennedy, Guardian writer Suzanne Moore, comedian Helen Zaltzman and broadcaster Shaun Keaveny. The debate about social class in Britain is more topical than ever, and we hope you'll join us and take part. We look forward to meeting you.
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