It was the worst of times, it was the worst of times.

It was the death rattle of a discredited Labour government and the birth of something monstrous: five days in 2010 that changed the country – not for the better.

Some people voted in the general election but many did not; the old Prime Minister tried to cling to power but found himself clutching at thin air; a rising star of the Left fluttered eyelashes at the Right; and some men in suits sat down in airless rooms to thrash out the future of Great Britain. They emerged 120 hours later with an ungainly, dangerous beast in their wake: a Conservative-led coalition hell-bent on helping the rich and stomping the poor into the dirt.

Five years on and the resulting Government has stained the political and social fabric of the United Kingdom like a toilet bowl in the aftermath of a dodgy takeaway. But how did this bunch of unelected chancers slither to the top of the greasy pole? Who put these naked emperors on the throne?

Although the apathy of the electorate and the failings of the first-past-the-post system are touched upon, Coalition does not apportion blame for the messy way the new administration was appointed. Nor does it retroactively judge the principal characters for the fallout from the decisions made during this time. Even Nick Clegg is dealt with sympathetically, although his subsequent demonisation casts a shadow over his every step.

Portrayed by Bertie Cavel as far more tortured than he has ever seemed in reality (the Nick Clegg Looking Sad Tumblr notwithstanding), Clegg sees glory within his grasp when his popularity surges after the first televised debate between the party leaders, but is brought back down to Earth when the Lib Dems end up with less MPs after the election than before.

However, with neither the Tories nor Labour gaining an overall majority, Clegg realises he can play kingmaker. But with which of his opponents will he form the first coalition government in Britain since 1945?

While Gordon Brown (Ian Grieve) prevaricates, hamstrung by the same over-cautiousness and chronic foot-in-mouth disease that cost him prior to the election, chinless simperer David Cameron (Mark Dexter) makes his move. Despite the warnings of Paddy Ashdown – whom Donald Sumpter plays as Obi-Wan Kenobi to Clegg’s Luke Skywalker, trying to save his protégé from turning to the Dark Side – the younger, more ambitious Lib Dems are already leaping into bed with a gaggle of Eton-educated Darth Vaders.

We know how this story turns out. It’s partly our fault (as Clegg points out, ‘People say they are sick of the same old politics, but every time you give them the chance to change, it’s “better the devil you know”’) and in any case the grim events of the last five years are impossible to forget.

Yet by only hinting at the horrors to come, Coalition functions more as a historical document than a morality tale: a snappily-written black comedy opera that expertly recreates a pre-austerity, pre-London riots, pre-Olympics period that seems much more distant than five years ago.

Clegg, Cameron and Brown come across as compelling if not wholly realistic (always a danger in dramas featuring people still in the public eye) and while the depiction of the secondary figures is as pared-down as the respective parties’ descriptions of their potential new colleagues across the table (‘Hume … marital difficulties’ … ‘Hague … Yorkshire … bald’) there’s nothing that doesn’t ring true. Not even Mark Gatiss’s haughty Hawtrey performance as Peter Mandelson.

Despite its many good qualities, though, it is to be hoped that Coalition is a one-off – or that if there is a sequel in five years’ time, it has a completely different cast of characters.

Airs at 9pm on Saturday 28 March 2015 on Channel 4.

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