AAs a teenager wearing Dr Martens in the 90s, I hated anarchist indie band Chumbawamba and their chart-topping anthem Tubthumping. (What a bunch of pranksters, I thought.) Well, I take it all back after watching this funny and surprisingly sweet documentary co-directed by frontman Dunstan Bruce and Sophie Robinson. It begins with Bruce, now in his late 50s, overwhelmed by a sense of helplessness as he ponders the future of the planet, wondering what he can do (“I’m a retired radical washed, rinsed”). As a filmmaker, he delights here a bit in wallowing: taking the negative voice in his head and bringing it to life, interpreted by an actor wearing a papier-mâché head, who gives a damn.

But from there, the film settles nicely into an enjoyable blast of pop history. Chumbawamba started as an anarchist collective in Leeds in 1982: living together in a squat, they went vegan (“I’m from Burnley! I didn’t like vegetables”), split the money equally and took turns to cook. . They had been going there for years when Tubthumping topped the charts. With a worldwide hit on their hands, the band decided this was an opportunity to do something positive – to be a political band in the belly of popular culture. They donated much of the money they earned, and in 1998 at the Brit Awards, singer Danbert Nobacon poured a bucket of cold water about Deputy Prime Minister John Prescott, furious at the Labor government’s treatment of Liverpool dockworkers.

Chumbawamba was massive in America and made the talk show circuit. (“If you can’t afford our music, steal it,” bandmate Alice Nutter said on late night TV.) In the present day, Bruce is interviewing their big US label boss of that period, who says that none of this has changed a thing. No one listened to the political message. “It went way over everyone’s head.” That’s what’s so unusual about I Get Knocked Down: it has a touch of humility that most music documentaries don’t. Bruce puts in the tracks that every other band on the planet would leave out. This includes a 90s montage of music critics lashing out at Chumbawamba. (“They’re not very good pop stars and they’re not very good political activists either,” is the damning verdict of a young Caitlin Moran.)

Chumbawamba broke up in 2012. They are still friends and seem extremely friendly here, not taking themselves too seriously at all. The scenes of them chatting together, laughing now, are adorable. The same goes for the end credits with YouTube clips of everyday people singing Tubthumping – everyone finds power and challenge in the song, from Christian choirs to heavy metal bands and little kids.

I Get Knocked Down hits UK cinemas on February 4.