Ken Loach could not have painted a more perfect, bittersweet picture for Cannes. Looking for Eric stars the French football legend Eric Cantona in a rare Loach comedy. Needless to say, it is a film of two halves. In the first, a postman called Eric Bishop is having a nervous breakdown. He drives the wrong way around roundabouts; the cupboards in his thoroughly grubby Manchester terrace are stuffed with unmailed letters; his black and white teenage sons from two broken marriages treat him like a doormat; and he’s still racked by guilt for leaving his first wife Lily, the love of his life.

Cue Cantona. How would the King handle Bishop’s crises? In a surreal and comic scene, the former Manchester United player steps out of a poster on the wall of Bishop’s rancid bedroom and dispenses gnomic gobbets of advice. It’s an extraordinary piece of magic realism for a director who usually specialises in art-house grit.

Cantona is basically a ghost, visible only to the delusional Bishop. His vague advice about how to handle Lily and the boys is delivered like poetry. Indeed, Cantona’s quote about sardines and seagulls — after he kicked a Crystal Palace supporter in the chest, earning a nine-month suspension — is central to this barmy comedy.

But the pleasure of watching a bearded Cantona playing life coach to the astonished and grateful Bishop is rigged, deliberately and brilliantly, with uncertainty. The morbid impression in the first half of the film is that Bishop has lost his marbles. His workmates and friends, notably John Henshaw’s bullish and kindly Meatballs, indulge Bishop’s delusion in a touching and desperate effort to put his life and sanity back together.

The second half is much broader and far less dark. There’s a dash of Woody Allen’s Play It Again, Sam about Paul Laverty’s script. Cantona takes the postman on training runs and turns up at Bishop’s local pub to have a chat about the importance of sharing problems. The sweet and healing chemistry between Steve Evets’ confused hero and Cantona taps a vintage Loach theme about the resilience and decency of human nature.

A marvellous scene in which Bishop quizzes Eric about his finest moment, while the two of them are watching old TV clips of Cantona in action, illustrates how the Frenchman believed in the ideal of the team more than in individual glory. That sense of solidarity goes straight to the heart of the film, in which a classic bit of old-fashioned teamwork is required to rescue one of Bishop’s sons from the clutches of a local gangster.

The upbeat way that Bishop goes about it with Cantona by his side has made Loach a strong favourite for the Palme d’Or. He won it in 2006 with The Wind that Shakes the Barley; but it would be a sensation if he did it with a comedy.

Editor's choice

• The 100 Best Films of the Decade
• 70 facts you didn't know about Marvel
• The 50 Biggest Movies Of 2010