For a while, it was considered unfashionable to be too overtly partisan in political theatre. Undermined, Danny Mellor’s hour-long one-man show about the mining strikes of the mid-eighties, lays that ghost to rest. Like Gary Owen’s electrifying Iphigenia In Splott, which turned heads last year at the National, Undermined is a gritty, somewhat in-yer-face monologue about a brutal government, a callous press, and a proud, unconquerable underdog. Where Iphigenia In Splott concluded with a threat, however, Undermined rallies the audience with a call for unity. Cynicism is out, principles are back.

Mellor, looking like what might have happened to Billy Elliot if he’d discovered lager before ballet, sits on a wooden chair on a bare stage, swilling a pint of amber as he relates his – or rather, his fictional character Dale’s – experiences through 1984 and early 1985, when Thatcher tried to reduce the pay of his South Yorkshire pit and his union voted in favour of striking. Mellor, as a multi-roling Dale, takes us through the strike’s early optimism, through it’s embittered and embattled peak – featuring a fierce and bloody recollection of Orgreave that is genuinely difficult to watch – to its proud, dignified conclusion.

But, despite the dulcet tones of Billy Bragg through the sound system, this is no sentimental reminiscing about battle scars and truncheon wounds. Undermined, perhaps because it has been closely informed by the diaries and recollections of men who lived through it, has an immediacy that is arresting throughout. Mellor channels this potency extremely well in a blistering, if slightly effortful performance. At first he captures a naïve enthusiasm for conflict with a beating chest and roaring Yorkshire spirit, then a tired but resolute determination to prevail, then an exhausted helplessness when his fighting spirit is finally crushed. At times he milks it, sure, but for the most part this emotional roller is sensitively but forcefully coasted.

There are a few moments of searing intensity: Orgreave is related like the pitched battle it was, with the sheer injustice of the police’s brutality realised in Mellor’s garbled commentary and wide-eyed terror; a galling late scene in which friend haltingly explains to friend his sobering reason for crossing the picket line is delivered to pin-drop silence. And there are a few moments of genuine humour as well: the laddish larks and japes of the miners are a regular source of comedy.

Mellor, together with collaborator and director Ben Butcher, has created something that neatly marries the personal and the political, and this is what makes Undermined so powerful: its bottom-up perspective of the fiercest industrial dispute of the last century. This plotting of the major events of the strike through the eyes of a simple, honest, hard-working miner means the one never outweighs the other. The human cost of Thatcherism is revealed compassionately, but the point is never laboured into polemical agitprop.

And it needs no pointing out that its stark encouragement of unity in the face of hardship inflicted by the state is piercingly pertinent right now, with the campaign for an inquiry into Orgreave gaining momentum in the aftermath of the Hillsborough verdict, and with Junior Doctors currently occupying the picket lines once valiantly manned by the miners.

Undermined played at The King’s Head Theatre until 16 May 2016. For more information and tickets, see The Old Red Lion Theatre website.