I'm not sure I would walk 500 miles and then sadistically walk the same distance again to prove my worth as a man.

Identical twins Charlie and Craig Reid, aka The Proclaimers, begged to differ in their infectious 1988 song I'm Gonna Be (500 Miles), which has become an anthem for Scotland's national football team.

Playwright Stephen Greenhorn drew inspiration from these lyrics, and the entire Proclaimers songbook, for his critically acclaimed 2007 stage musical, Sunshine On Leith, charting the romantic dalliances of two friends who return home from a tour of duty in Afghanistan.

Actor turned director Dexter Fletcher harks back to his early role as Baby Face in Alan Parker's Bugsy Malone, to harness the exuberance of the stage show on the big screen.

This is an unabashedly feel-good romp through matters of the heart that underscores its soap opera narrative with slickly executed song and dance sequences.

Admittedly, the set-ups are as hopelessly contrived as Mamma Mia!.

One character decides to leave Edinburgh to pursue their career in Florida to make sense of the lyric "Take a look up the railtrack/From Miami to Canada" in Letter From America, and a mother figure is named Jean so her husband can serenade her with Oh Jean.

Fletcher's film is most powerful when it defies expectation.

The title track resonates deeply as a hospital bedside lament, sung over the body of a gravely ill spouse, and when squaddies sing Sky Takes the Soul in the confines of a tank, the omens of impending doom are unmistakable.

Davy (George MacKay) and best mate Ally (Kevin Guthrie) return home to Leith after a roadside explosive kills one of their band of brothers.

Ally falls into the arms of his girlfriend Yvonne (Freya Mavor), who is Davy's sister, while Davy kindles romance with Yvonne's best friend, Liz (Antonia Thomas).

Both relationships blossom and Ally buys a ring, intending to go down on bended knee at the forthcoming 25th anniversary party of Davy and Liz's parents, Rab (Peter Mullan) and Jean (Jane Horrocks).

A dark secret from the past threatens to tear the family apart, propelling the characters along divergent paths.

Sunshine On Leith is shamelessly sentimental, tugging heartstrings with abandon, but the joyfulness gradually wears us down until we're powerless to resist.

MacKay, Guthrie, Thomas and Mavor sing their parts with conviction and charm, while Mullan and Horrocks lend emotional gravitas as a long-time married couple in emotional crisis.

Musical sequences are delivered with gusto including a beer-soaked rendition of Let's Get Married in a bar, which is countered by Hate My Love as young dreams turn sour.

The Reid twins enjoy a cameo early in the film, proving they will walk 500 yards on camera for Fletcher and co.