Kenneth Branagh’s idealisation of his home city before the Fall plays out to some of Van Morrison’s most soothing melodies. Makes sense. We join Belfast in the last year of the 1960s – as the Troubles surge and Morrison’s first great solo period peaks. Indeed, the whole film plays like one of the singer’s later, sentimental, spoken-word pieces. Gently tapped brass. Tinkly piano. “Matchbox cars. Chitty Chitty Bang Bang. Soap flakes. Thunderbirds are go. Don’t you wish it could be like this all the time?” Aggressively apolitical, Belfast will do little to educate the wider world about the inequalities that fertilised the coming violence. But, as romanticised reverie – black-and-white and rose-tinted all over – it could hardly be bettered.

The film has taken so long to get here it feels as if it has already been through two or three complete critical cycles. A hit at Telluride and Toronto, where it won the influential People's Choice Award, Belfast is, with most bookies, still marginal favourite for best picture at the Oscars. Why not? A clatter of the era's best actors engage joyfully with the director's economic, autobiographical screenplay. Caitríona Balfe and Jamie Dornan are knitting-pattern gorgeous as parents to newcomer Jude Hill's cheeky young tyke. Ciarán Hinds and Judi Dench manage the platonic ideal of kindly Ulster grandparents. Shot largely on clean sets, the film stages its riots like dance numbers in a golden-age musical. The word "irresistible" is, well, hard to resist.

We begin with a title sequence that is a little too close to a Fáilte Ireland commercial for comfort. Cut to a new, indifferent Morrison song, the montage takes us past colour images of contemporary Belfast before peering over a fence and encountering a black-and-white idyll. There are shades here of Alfonso Cuaron's Roma (which Branagh hadn't seen when he began production), but we are closer in spirit to Terence Davies's equally autobiographical The Long Day Closes. In both films, set only a few hundred miles apart, a stand-in for the young director escapes from the everyday at his local flea pit. Lest we be in any doubt as to the filmmaker's intentions, young Buddy is seen reading a Thor comic – a character later adapted for the MCU by Branagh. Unlike Davies's version of Liverpool, this take on Belfast seems scarcely less glamorous than the images screened at the neighbourhood Odeon. Why bother with High Noon when you have equally attractive variants on Gary Cooper and Grace Kelly at home?

That winding in of escapist pop culture with the film's heightened reality hits a crag when Buddy's Da explicitly takes on the Cooper persona as loyalist hoodlums circle. Despite the rising strains of Do Not Forsake Me, the misguided scene is less suggestive of High Noon than of a Milky Bar commercial. Elsewhere the filmmakers just about get away with the balancing act. Having committed himself to a sunnier take on potentially harrowing material, Branagh is wise to tiptoe around the sectarian politics. The religious jokes are mostly at the expense of the family's Protestant preconceptions. "I've nothing against Catholics, but it's a religion of fear," one of the community says. We then cut straight to a non-conformist minister yelling about an "eternal pit of suffering". Greater divisions loom for working-class communities that then still enjoyed a degree of integration.

As we might expect from a Branagh film, the few moments of awkwardness are nudged aside by consistently excellent performances. Hill stays just the right side of cute. Balfe and Dornan confirm their status as cask-strength movie stars. Hinds twinkles as a wise old rogue. Dench, a long-time collaborator of the director, has the smallest of the five big roles, but makes the biggest impact with a brief, late speech that could draw tears from a barmbrack. With worries gathering around the fictional parents and our nagging knowledge of Branagh’s ultimate removal to Reading, we always know where the story is heading, but that does nothing to dull its ruthless emotional twists.

A gorgeous, proudly unreliable glance over the shoulder. A tribute to an often maligned city. No doubt a source of incoming controversy. What else would you expect from a film called Belfast?

Opens on January 21st