It is 27 years since Hope and Glory, John Boorman´s fond film a clef about Blitz survival and wartime British pluck. It may not have felt like a picture crying out for a sequel, but name one Boorman film that ever has done. In a radical and shape-shifting 50-year career, the Shepperton-born director has jumped from hard-boiled revenge thriller (Point Blank) to absurdist war film (Hell in the Pacific) to primal buddy movie (Deliverance) to bonkers sci-fi (Zardoz) to Arthurian fantasy (Excalibur) to ecological adventure (The Emerald Forest) to le Carre portraiture (The Tailor of Panama) – finding time to make one sequel, to someone else´s film, that could hardly be any less like it (Exorcist II: The Heretic).

Queen and Country, which has premiered in the Director´s Fortnight strand at the Cannes Film Festival, is a no-fuss companion piece to Hope and Glory, picking up where that one left off, as if no time had intervened between them at all. We could have guessed from Boorman that the setting, at least, would be totally different: not the bombed-out London suburbs, but a military training base at the start of the Korean War in 1952. The film rarely leaves these confines, except when 20-year-old Bill Rowan (now played by the stoically good-looking Callum Turner) pays the odd visit back to his family, who live, as you may remember, on a quaint little island in the middle of the River Thames. The wartime dalliance between Bill´s mother (Sinead Cusack) and another local fellow is a thing of the past, though these former paramours wave to each other silently and daily as he passes her house, and dad (David Hayman) sits at the table grumbling over the papers.

The film´s a gentle pleasure, going nowhere particularly fast. There´s an episode involving cigarettes drowned in strawberry jam. The only pivotal narrative incident is the carefully plotted heist, for sheer larks, of a regimental clock in the mess hall. Though we perhaps expect Bill to be shipped off to Korea, it never happens: he´s involved in training corps cadets with his friend Percy, a roustabout ginger posho in which role the antic, effortful Texan actor Caleb Landry Jones (Antiviral) is perplexingly miscast.

Luckily, he´s the only person in the film who is. The supporting cast is a trove of pointedly comic character playing: Pat Shortt is a hoot as the irreverent, cowardly and ageing Private Redmond, Brian F. O´Byrne irascible and equally funny as his pompous RSM, against whom the clock-nicking is partly targeted. David Thewlis, looking almost eerily like Arthur Lowe in Dad´s Army, is a by-the-book Sergeant Major maddened by war and obsessed with protocol; Richard E. Grant is the aptly named Major Cross, the weary bureaucrat in charge of them all; and there´s one great scene for Julian Wadham, as an exasperated court-martial judge who just wants the whole thing over with.

Boorman has written and cast these roles with a twinkle in his eye, but no one gets caught playing to the gallery; the film´s visually a little pedestrian, but it´s not dull-witted. It takes shape as an institutional comedy in the boisterous British tradition of Porridge or If…, though its closest filmic model might be the 1988 Mike Nichols version of Neil Simon´s conscript-training romp Biloxi Blues.

Above all, it´s a sincerely personal piece for Boorman, who relishes the chance to revisit the key moments of his film-buff education, and indeed life education. When Bill and the girl he´s wooing (Tamsin Egerton) emerge from Kurosawa´s Rashomon, she interrupts his geeky enthusiasm for that film´s famous multiple perspectives with the entirely fair comment that, in every version, “the woman´s always raped”. There are other, precise and period-appropriate nods, to Sunset Blvd and Strangers on a Train. It´s almost a given that Boorman will end his film with the shot of a camera whirring on the Shepperton riverbank, an obsession of his own fast falling into place. Admittedly modest, but the epitome of jolly, this is like the companionable second volume of an autobiography in film form – you´ll whip through it in no time, and come out wanting more.