A Walk on Part at the Soho Arts Theatre is adapted from the diaries of former Labour MP Chris Mullin, and tells the epic journey of New Labour, from the 1997 general election to their defeat in 2010.

As with any performance dealing heavily in politics, it runs the risk of being dry. But Michael Chaplin’s adaptation, in this case directed by Max Roberts, is fast-paced, witty and insightful, all the while managing to retain Mullin’s voice: visionary, worrisome and totally endearing.

The cast comprises of five actors, but the central figure is Mullin, played superbly by John Hodgkinson with his wonky posture, mad professor hair and clothes that don’t quite fit. His resemblance to Quentin Letts’ Mullin description is uncanny: “His trousers flap eminently around his shins, his sparse hair is unkempt, his spectacles could do with a polish, and his manner of speaking is gentlemanly. He resembles a deckchair that’s been left out all winter.” Hodgkinson narrates the plot, snapping effortlessly between monologue and dialogue and knowing Mullin’s story inside out.

The other actors multi-role between various political and media figures, the most notable being Hywel Morgan as Tony Blair, whose intonation, gesture, and facial movements give Dead Ringers’ John Culshaw a run for his money, and Joe Caffrey as Gordon Brown, complete with stoic frown and signature jaw-drop. Others are John Prescott (or “JP” to Mullin), Geoff Hoon, Claire Short, and Tony Benn. All the cast wear a hint of Labour’s red: a tie, a flash of shirt, shoes.

The stage is bare other than two rows of four chairs, accommodating the actors when they aren’t in role, and a stack of 90s television screens embedded in the back wall, which provide the dates of Mullin’s entries, bookmarking the episodes in British political history.

But their function goes further than that: when Blair enters Downing Street, his smirk and wave is reflected and multiplied in each screen; when the Guardian’s Michael White calls Mullin on the 11 September 2001 and tells him to turn on his TV, that all-too familiar image of aeroplanes crashing into the World Trade Centre silences the auditorium. 9/11 was, for so many people, beyond comprehension and even reality; we associate the event with what we saw on TV, and Roberts’ interpretation is a nod to the sensationalism of its coverage.

The TVs provide general illustration to the plot: stills of the House of Commons during PMQs, various MPs, and humorously, Steve Bell’s magnificent cartoons, namely the infamous Gordon Brown, slumped and defeated in a boxing ring after the 2010 election, and the depiction of David Cameron with a condom stretched over his head.

But their illustration does not go as far as to draw attention away from the action. Mullin’s diaries reveal an awful lot about himself and the Labour Party. He is wholly idealistic, voting against the invasion of Iraq and confronting former Defence Secretary Geoff Hoon on the targeting of civilians in Afghanistan. In such a cynical age, it is refreshing to experience an MP who is non-deferential, speaking his mind and following his heart. But even Mullin becomes pessimistic about what he can achieve as a politician: from the disillusionment as a junior minister in Prescott’s environment office, to his inability to improve the lives of Ukranian asylum seekers, to his work as Africa Minister at the Foreign Office.

We are also fed snippets of Mullin’s family life. His devotion is touching, particularly given the Westminster context of seedy affairs and marital neglect. We witness his mother’s health deteriorating and his daughters growing up, and when he finally steps down, it is for his wife.

Chaplin has tweaked Mullin’s diaries to highlight the symmetry between past events and what we know today. As soon as Labour is elected, there is the question of Rupert Murdoch and the Competition Bill - John Major goes so far as to say that Murdoch has “done such damage to this country”. Mullin is outspoken in his recognition that a life of consumerism is not sustainable for the economy nor the environment, a conviction all the more urgent as we are steeped in both financial and climate chaos. His reluctance to go into war is all the more poignant more than ten years since the invasion of Afghanistan, and when the British death toll surpassed 400 earlier this year.

A Walk On Part is an excellent dramatisation of Mullin’s revealing diaries that tell us a great deal about the political landscape of the past 15 years, captivating the audience in a world that is all too relevant today.

A Walk On Part is at the Soho Arts Theatre until 14 July