Pauline "Poppy" Cross (Sally Hawkins) has an irrepressibly sunny outlook in the Mike Leigh film Happy-Go-Lucky. (Maple Pictures)

You have to be wary about a Mike Leigh film with a cheery title. High Hopes (1988) dealt with the plight of the working class in Thatcher-era Britain; Life Is Sweet (1991) concerned a family with a bulimic daughter. I went into his latest picture, Happy-Go-Lucky, fully expecting a similar kind of irony. What a surprise! This turns out to be the British writer-director’s most upbeat work since his 1999 Gilbert and Sullivan comedy Topsy-Turvy. Without forsaking his trademark kitchen-sink realism, Leigh has crafted a non-ironic ode to optimism that acts like a tonic in these gloomy times.

With Happy-Go-Lucky, he offers us one of his most charming characters: Pauline “Poppy” Cross, played with beguiling buoyancy by Sally Hawkins. Poppy is just what her nickname suggests – all bubble and fizz, bangles and rings, teasing and quips, topped off with an irresistible, yard-wide smile. She is a primary school teacher, the sort with boundless enthusiasm, the kind you always hope your kids will get. Her energy overflows outside the classroom – she works off the excess each day by bouncing on a trampoline – and it comes with a resolute lightheartedness. When Poppy’s beloved bicycle is stolen in the movie’s first scene, she’s momentarily perplexed, then shrugs it off. “Didn’t even get a chance to say goodbye,” she jokes, then goes off and enrolls in driving lessons.

Some people – like her married and pregnant younger sister – might write off Poppy as a case of arrested development. Here she is, 30, single and still acting like a college kid: sharing a rented London flat with her best mate, fellow teacher Zoe (Alexis Zegerman), and spending her weekends down at the pub, getting drunk and giggly with her girlfriends. Others may see her silly behaviour as childish and her knee-jerk empathy for everyone she meets as naive. But Poppy can be mature when she needs to be. When she encounters a nascent bully among her students, she handles him with sensitivity and insight; she defuses his aggression with kindness and makes sure he gets the help he needs.

Adult bullies are a bit more of a challenge. Scott (Eddie Marsan), her driving instructor, turns out to be one of them. Humourless, autocratic, he’s a fiery-haired bottle of barely contained rage, and Poppy’s relentless high spirits nearly make him mad. In the course of their lessons, he tries to impart his pessimistic worldview to Poppy. Marsan is scary-hilarious in the role; his hatred and suspicion of everything have turned him into a conspiracy theorist – the kind who sees signs of Satanism in the Washington Monument. Poppy has him pegged fairly quickly: “Were you bullied as a child?” she asks astutely.

Driving instructor Scott (Eddie Maran, foreground) shares his bleak view of the world with Poppy in Happy-Go-Lucky. (Maple Pictures)

The film uses Poppy’s weekly driving lessons as a through-line on which to string a series of episodes in her life. After she injures her back on the trampoline, Poppy decides to try a slightly less strenuous flamenco class, taught by a wildly passionate Spaniard (played by the delightful Karina Fernandez). Later, Poppy, her moody youngest sibling, Suzy (Kate O’Flynn), and the acerbic Zoe pay a weekend visit to Poppy’s married sister, Helen (Caroline Martin). While Helen is an uptight killjoy who urges Poppy to start climbing the “property ladder,” Helen’s nebbish husband (Oliver Maltman) turns out to be a big kid at heart. Romance eventually materializes for Poppy in the hunky form of Tim (Samuel Roukin), a social worker who shares Poppy’s sensitivity and – just as importantly – her sense of humour. Scott, who despite his exasperation has a secret crush on Poppy, sees them together and his jealousy boils over.

Leigh is famous for developing his scripts and characters in collaboration with his actors. That may be why even the minor roles in Happy-Go-Lucky are distinctive. And why, in the short scenes between Poppy and her sisters, an entire family dynamic is already in place – you even notice their physical resemblance, forgetting for a moment that these are actors, not real siblings. Like Poppy, Leigh is full of compassion for even his most twisted subjects: Scott, for all his spitting rage, is finally sad and pitiful – Marsan makes him look like a trapped rodent, gnashing his pointy little teeth at the world.

But the film belongs to Hawkins. Although she played secondary roles in Leigh’s All or Nothing (2002) and Vera Drake (2004) – and the lead in a television version of Jane Austen’s Persuasion – she has been largely unknown outside the U.K. That should change with this breakout performance, which has already won her the best actress prize at the Berlin film festival and could well give her a run at the Oscar. Poppy, a female Candide minus the innocence, is one of the most engaging creations to hit the screen this year.

Leigh presents her sunny outlook without cynicism and that’s what validates the movie. This is a 65-year-old filmmaker who has probed the dark side of human behaviour (see his Naked and the heartbreaking Vera Drake), but can still see the world in bright colours, through Poppy’s laughing eyes. When Happy-Go-Lucky is over, you leave the theatre walking on air.

Happy-Go-Lucky opens Oct. 17.

Martin Morrow writes about the arts for CBCNews.ca.