To reach the home of director John Boorman, take a car south out of Dublin and point it at the hills. Once off the motorway, the modern world drops away and the population thins out. The car comes darting through sleepy villages and past primitive pubs; across foaming green rivers and up into the old Celtic grounds around Glendalough. It feels as though we are riding deep into the past.

Fixing coffee in his kitchen, Boorman explains that he bought the house for a song in the late 60s, when his career was still young and the family still growing. Now he lives here alone, surrounded by woodland on all sides. At the age of 82, he has taken on the lean, ascetic quality that comes to some men late in life, when they’ve shrugged off the baggage of fat-cat middle-age. He says: “If you look around 360 degrees, you see nothing but trees.” He jokes that he has started to worry that he prefers trees to people.

John Boorman. Photograph: Jeremy Craine

Boorman has been making his rich, thorny pictures for a half-century now; a process he describes as turning money into light. His career runs the gamut from the steely enigma of Point Blank through Deliverance’s hand-tooled backwoods horror, the cock-eyed abandon of Zardoz and Excalibur to the hothouse mysticism of The Emerald Forest. But his new film, tellingly, is an altogether more gentle and affectionate enterprise – a period piece that resets the clock and brings the director full circle. Still more tellingly, it ends with the sight of a camera winding down on its tripod at the side of the Thames.

Coffee prepared, we sit by the window and discuss Queen and Country. He allows that the film can be read as a dramatic memoir, a sequel-of-sorts to the Blitz-era Hope and Glory in that it nudges the action forward to 1952 when Boorman surrogate Bill (Callum Turner) is 19 years old and completing his national service. The tale throbs with personal reminiscence, whether it be a fraught prank involving a stolen clock, the painful acknowledgement of his mother’s affair or the comical sacrament of Boorman’s first cigarette (soaked in strawberry jam and dried out on a stove). He was striving for clarity; trying to show exactly how it had been. But the actual process of filming has a way of seeping into the story, as condiment seeps into a cigarette mailed from home.

“The relationship between memory and imagination is very mysterious,” he explains. “If you tell me a story about something that happened on the way here from the airport, you are already applying imagination to memory. And it’s the same thing with the film. The one thing I always regretted about Hope and Glory is that it was based on my childhood memories, and now I have lost all those memories and can only remember the film. And now this has come along and usurped my memories as well. That scene with my first cigarette, for example, it was such a vivid memory. It does not feel so vivid any more.”

He adds that he recently screened the film for his teenage son, Lee. When the end credits rolled, he asked him for his verdict. “Well, I was a bit bored,” Lee admitted, “because I know all of those stories.”

And yet Queen and Country amounts to more than a series of acted-out anecdotes. It is about the political as well as the personal. It spotlights dissent within the ranks and installs the stolen clock as a kind of ridiculous proxy for a defunct British empire. Here is a world in which Victoria scowls from the wall of the officers’ mess, while the privates stick Jane Russell posters above their beds in the barracks. The gauche virgin soldiers know the old order has fallen, even if the commanders do not.

“The early 50s seeded so much social change,” Boorman says. “We lost the empire but gained the National Health Service and the secondary modern school. For the first time, every kid was taught some element of music and art. And the kids who were going to these schools grew up to be the Beatles and the Rolling Stones. Even at the time, we knew what was happening. That the whole Churchillian thing was pretty much over. That the whole empire was about to collapse.”

Liberated from national service, he worked in the newsroom at Southern TV and then went on to shoot documentaries for the BBC. In the mid-60s, he directed a boisterous pop musical (Catch Us If You Can, featuring the Dave Clark Five), which was lavishly praised by Pauline Kael and provided him with his ticket to Hollywood. His life opened out; his career sparked and bloomed. If he could rewind to 1952 and reprise the entire trip, he cannot imagine exactly what he would change. Boorman frowns. “Actually, I can’t even contemplate it. I’m a completely different person now. Occasionally somebody will come up and say: ‘Oh, I love Point Blank.’ And I want to say: ‘It was made by somebody with my name but quite different from me.’ I made those early films out of fear and daring. Once you get to the point where you understand the process, you can never work in that state of innocence again.”

Burt Reynolds in Deliverance. Photograph: Moviestore/REX

He sips his coffee, surrounded by his trees and his books, and recalls his friendship with men such as Akira Kurosawa and Stanley Kubrick, Lee Marvin and John Huston – all of whom are now long dead and gone. He talks of those faraway films that were made by a man named John Boorman and confesses he has a good deal of time for them still. He shot Excalibur (his delirious take on Arthurian myth) in the woods by the house and concedes that the film was so wild that it almost got away from him. The post-apocalyptic Zardoz, too, was shot in the neighbouring hills. Sean Connery once prowled these lonely bridleways, resplendent in a scarlet mankini, his plaited ponytail waving in the breeze. Nowadays, of course, Zardoz enjoys an ardent cult following, but it was reviled at the time; no one could figure out what it meant. Boorman smiles. “Nor could I actually. But that’s OK. Or I think it’s OK.”

If he had to pick one film above the rest, he supposes he would opt for Deliverance. This 1972 classic manages to be both muscular and mysterious, brutal and nuanced, as it dispatches four middle-class canoeists (Jon Voight, Burt Reynolds, Ned Beatty, Ronny Cox) down the rushing river towards their own heart of darkness. The director says the film is perfectly composed, not a frame out of place, although he marvels at the health-and-safety standards that he breached on the way.

Lee Marvin in Point Blank. Photograph: Getty Images

“Certainly, Deliverance would be impossible to make today,” he concedes. “You’d have to have a risk-assessment officer on hand at all times. All we had was a diver with us. And he did have to go into the river and pull people out. One day Ned Beatty went down and he didn’t come up. He was gone, I don’t know, maybe two minutes or so. I always had the fear I was going to lose one of the cast.”

Queen and Country ends with Bill’s camera winding down and clicking shut. But it also, significantly, ends right back at the river. It strikes me that the river has always been central to Boorman’s life and work. The man was raised near Shepperton studios, on the banks of the Thames. The river roars unchecked through the boondocks in Deliverance. It plays the role of imperilled wellspring throughout The Emerald Forest. The director explains that there is also a river flowing right through his land; it’s the main reason he bought the place to begin with. He likes to look out at the trees and hear the running water.

Boorman filming The General, 1998. Photograph: Mondadori via Getty Images

Interview complete, we prepare to climb into his car and drive out for some lunch. Standing in the driveway, he points out the river with its narrow sword bridge. Further downstream, where the water is deeper, he has a swimming hole and a diving board. He says: “When the weather is warm I go down there and swim. And I commune with the river. And recently the river has been saying to me: ‘Come on in and follow me down to the sea.’ And it is rather inviting. But I said: ‘Not quite yet. Give me a couple more years.’”

The car slaloms and scrapes down country lanes to the village. The pub on the high street provides oysters, rollmops and Guinness. The pub is terrific and I’m enjoying our lunch. I advise him not to pay too much attention to the river’s advice, or at least tell the damn thing to wait until the bar-taps have run dry.

Queen & Country is released in the UK on 5 June