Another of Leigh's trademark slice-of-life British comedy-dramas, using generally unknown (to Americans) actors who work with their director for months in improv workshops in order to develop fully lived-in, realistic characters, Happy-Go-Lucky's heroine is a 30-year-old Londoner named Poppy (Sally Hawkins) who is thoroughly unflappable in her optimism no matter the situation

Leigh gauges our tolerance for such an exuberantly happy person right up front when, after Poppy fails to engage a surly bookshop employee in conversation, she finds her bicycle stolen and says simply, "Oh no! I didn't even have a chance to say goodbye!" Thankfully, this is the most outlandishly Pollyanna-ish Poppy gets. Leigh is no sentimentalist. Nor is he a sadist: an endlessly giving character like Poppy would become a sacrificial lamb if placed in a Lars von Trier film, but while Leigh does examine the downside to being nice to everybody, he does so in a non-melodramatic manner that is truer to reality, and truer still to his characters.

Sally Hawkins is wonderful, but the whole cast is great, especially Alexis Zegerman as Poppy's gruff but lovable roommate and Eddie Marsan as Scott, Poppy's driving instructor, possibly the angriest man in England. The interaction between Poppy and Scott drives what little narrative the film has, and it's a pleasure to watch these two actors together.

What Leigh does is interesting in that most of the characters in the film are teachers of some sort. (Poppy, unsurprisingly, teaches little kids.) I'm still not entirely sure of the relevance here; perhaps Leigh sees teachers, whether happy or frustrated, as idealists. Indeed, Happy-Go-Lucky is about the bravery it takes to be an idealist, to be optimistic in a world that is anything but. (The film is shot in the plainest, most soulless areas of modern London, emphasizing the difficulty of keeping a free spirit in a place devoid of character.)

I find this film endlessly thought-provoking and, in its way, inspirational. As one critic said of Poppy, I believe Leigh the utopian sees her as the next evolutionary step for humankind; a woman out of place in 2008, perhaps, but a hopeful sign of what could be around the corner. To call Happy-Go-Lucky a "feel good" movie would be dismissive; it's a real drama, with real characters and real darkness. But in reminding us of the responsibility we all share in making the world a happier place, it is the sweetest and perhaps the most important film of the year.