When director Ken Loach turns his attention to the Irish question he always attracts a flurry of right-wing indignation amid accusations of an anti-British stance.

After Hidden Agenda prodded Daily Mail commentators into an apoplectic fury when it tackled Britain's "shoot to kill" policy, this chronicle of the origins of the IRA has already had them reaching for their poison pens.

Through the eyes of bright medical student Damien (Murphy), we watch as an easy-going gang of lads are radicalised into footsoldiers of a volunteer guerrilla army - the embryonic IRA.

The reason why is simple - the vicious heavy-handedness of the Black & Tans, the ill-disciplined British force drawn from the trenches of World War One.

The decision by parliament to despatch this rabble of borderline psychopaths was akin to throwing a bucket of petrol onto a bonfire - any chance of winning the "hearts and minds" of the politically neutral was stamped out overnight.

So we have Damien looking on horrified as a childhood friend is murdered for refusing to speak his name in English and all plans for training to be a doctor in London are abandoned.

Going to ground, he becomes a leading member of an IRA "Flying Column" alongside his driven, taciturn brother Teddy (Delaney), stealing arms from barracks and ambushing British Army columns.

Among its ranks he meets Dan (Cunningham), a thoughtful William Blake-spouting republican veteran and socialist, who inspires him with his quiet, dignified pragmatism.

However, what starts out as an almost Dad's Army movement replete with big flat caps and wooden rifles soon hardens into a political beast of Gordian complexity.

As the IRA assumes a cool professionalism and diamond hard-edge, the blurring of its political goals - democratic socialism versus simple rejection of British rule - gives rise to nagging self-doubt.

Rather than stark pro-IRA storytelling, Loach has taken a historical snapshot of a groundbreaking time in its evolution - fast-forward fifty years and republicans with the same ideals are blowing up innocent civilians in Birmingham pubs.

Admittedly, some weighty political debates are clumsily shoe-horned into the narrative and the British forces remain stereotypical thugs with little effort to explain their actions or motivation.

Nevertheless, thanks to terrific performances all-round - Cunningham is superb and Orla Fitzgerald affecting as Damien's lover Sinead - it's never less than compelling and ultimately provides a heartwrenching dilemma of blood over political conviction.

Ignore the conspiracy theorists who interpreted its winning of the Palme D'Or at Cannes as some sort of comment on September 11 - just enjoy it for what it is…an engaging piece of work from a director back on form.

Tim Evans