It would be, it has to be said, disarmingly easy to make a case against The Wind That Shakes the Barley based on its first half-hour. It's an absolutely partisan movie and never pretends to be otherwise, but its largely one-sided presentation of this bit of Irish (and British) history inevitably suggests over-simplification of a complex situation. British soldiers are repeatedly shown brutalising the locals, while the opposition are, it has been suggested in some quarters, somewhat romanticised.

Consider the opening ten minutes. It's 1920, and a group of very likeable Irish boys return home after a hurling match and are almost immediately descended on by a band of British soldiers, who hold them at gunpoint, verbally and physically abuse them and beat one of them to death for his non-cooperation. One of the locals, Damien, is a promising young doctor, a man prepared to dedicate his life to that most noble of causes, the saving of human life, a polar opposite to the brutes that invade his village, bad guys as evil as any martial arts or Bond movie villains. In a later scene, when the boys are forced to stay in hiding while more soldiers descend on their home and attack their womenfolk, one of the attackers actually laughs maniacally as he cuts the hair from a woman's head. At this point the film genuinely, for just one dangerous moment, risks teetering over into melodrama.

It is this seemingly unquestioning division between the good and the bad that so riled certain quarters of the British press. Well that and the fact the good guys here are members of the Irish Republican Army, an organisation they regard purely as terrorists and whose existence and actions they have no interest in seeing justified in any way. And to suggest that British soldiers would ever, ever behave in such a fashion is, they believe, tantamount to treason.

And yet history tells a rather different story. The Black and Tans, as they were known, were recruited on the promise of a good wage and were required to be ready to "face a rough and dangerous task." They were first sent to Ireland in 1920 to assist the Royal Ulster Constabulary, who were coming under increasing attack from those fighting for an independent Ireland, free of British rule. Although many of the recruits were ex-WW1 soldiers, discipline and especially self-discipline in the Black and Tans was poor, and they responded to attacks on their numbers by terrorising the local population, burning down buildings and carrying out reprisal killings, fuelling a tit-for-tat war with the IRA activists that only served to worsen relations between the Irish population and the British occupying force.

It's not a bad idea to read up on this stuff before approaching The Wind That Shakes the Barley for the first time, as it provides the context for the drama that unfolds and a reasoning for the chosen viewpoint. Loach, together with regular screenwriter Paul Laverty, are not documentarians but dramatists, and their position here is not to provide an even-handed history lesson, but to explore the experience of living under and actively resisting a sometimes brutal occupying army. While this theme has been explored in any number of films in the past 60 years or so, the response of the more conservative (re-) viewer seems to dramatically shift when the oppressed locals fight back under the banner of a united Ireland, and the oppressors speak with English rather than German accents. And they really are bastards here – the film's first quarter features a succession of violent acts committed against civilians and guerrilla fighters alike, from verbal abuse to violent assault and torture (the second fingernail-pulling scene I have winced through this year after Syriana). It's certainly bludgeoning stuff, as it was no doubt meant to be – at our cinema screening we had a number of walk-outs even before the halfway mark was reached.

In dramatic terms this provides justification for the first retaliatory acts, but it soon emerges that Laverty and Loach's view of events is far from the simplistic one that these early scenes or their tabloid critics might suggest. The IRA's retaliatory action initially inflames the conflict, taking and executing hostages has serious moral consequences, and victory leads not to peace but divisive in-fighting. It's a question facing all revolutionaries, how to manage the peace if you win the battle, and what compromises should you be prepared to make to maintain it. This is embodied (a little too neatly perhaps) in brothers Damien and Teddy, initially united in the armed struggle against the British but later increasingly divided on the shape an independent Ireland should take.

Political issues feature large in the second half, and it's once again in the staging of group discussions that Loach's observational approach shines the brightest, the documentary-like debates presenting both sides of the topics under discussion in a compelling and intelligent manner, much as they did in earlier works such as Riff Raff and Land and Freedom. The similarities to the latter film (which was scripted by the late Jim Allen) extend to structural and narrative elements and even specific scenes, and if, for myself at least, The Wind That Shakes the Barley stands a little in its predecessor's shadow, that should not take anything from the younger film's considerable and persuasive dramatic power.

As ever with Loach, the performances are both naturalistic and committed, the sometimes fierce but all-too-real aggression of the Black and Tans coming not from drama school training, but by having them all played by ex-British soldiers, men trained and experienced in situations where forceful tactics can be standard operating procedure. As Damien and Teddy, Cillian Murphy and Padraic Delaney both give their all, but special mention should go to Liam Cunningham as Dan, the voice of experience and reason of the group and a reminder of the contribution of organised labour to the cause, steadfast non-compliance their key weapon.

The Wind That Shakes the Barley has the qualities of an angry polemic but is far smarter than such a label might suggest. Although exploring events from the republican viewpoint and providing repeated justification for retaliatory action, it also suggests that this pulls both sides into a spiral of violence that is destructive to all and ultimately solves little. It's a lesson that is still relevant today, wherever invading troops become armies of occupation (do I really have to elaborate?), and it is this inevitable association that really gives the film a topical bite, despite its historical setting. It may not quite be up there with the very best Loach (and that's a subjective call anyway), but it's still a compelling and very impressively realised piece from Britain's most politically cimmitted and consistently impressive filmmaker, and one that, after seven nominations lost out to others, thoroughly deserved the Palme D'Or win.

The Anamorphic 1.85:1 is for the most part very good, but is at times something of a mixed bag. At its best it boasts impressive sharpness, contrast and colour, but on occasion (usually dark interiors) is noticeably grubbier, with weak contrast levels and visible compression atefacts. This can vary from shot to shot, most evident in the prison scene, where minor variations in lighting are dramatically amplified by the transfer.

The 5.1 surround track is, as you'd expect for a Loach film, a clearly recorded but low key affair, with with separation and surround work kept to a minimum and never drawing attention to itself. Music is effectively spread.

This is a 2-disc release and the only extra feature of disc one is a Commentary by Ken Loach and Historical Advisor Donal O'Driscoll. Those of you who sat patiently through the lengthy silences on Loach's commentary for Sweet Sixteen need not worry – this is a far busier affair and an essential companion to the film, with Loach and O'Driscoll providing a great deal of historical and political background to the drama, while Loach provides details on the actors. A consistently interesting listen that deepened my appreciation of the filmmakers' intentions and achievement.

On disc 2 the main feature is the documentary Carry on Ken (46:56), originally screened on Channel 4 (or was it More 4?) that provides an entertaining look at Loach the film-maker, his career and working methods, with contributions from many of those he has worked with.

The Theatrical Trailer (1:55) is a pretty good sell.

The Photo Gallery has 20 press photos for the film, all at a reasonable size.

If you, like me, thought The Wind That Shakes the Barely was a tad heavy-handed on the first viewing, then I strongly recommend a little research and maybe even the Loach and O'Driscoll commentary before giving it a second shot, and I can almost guarantee you'll be more receptive to Loach and Laverty's approach. It's not always comfortable viewing, nor should it be, but it's still in my book a top contender for best British film of the year.

As for the disc, well it's the same old gripe, the words "2 disc Special Edition" on a release that could have fitted the film and the only substantial disc 2 extra on a single DVD. But it's a good documentary, and the feature commentary is Loach's most informative and compelling yet. So yes, it still comes recommended.

* Quoted from The History Learning Site article, The Black and Tans, http://www.historylearningsite.co.uk/black_and_tans.htm