Sheffield Doc/fest

One such is Scarlet Road, a touching Australian film looking at the life of Rachel Wotton, a prostitute working in New South Wales - one of the few places in the world where selling sex is decriminalised.

Likely to inflame supporters of the "Swedish model," this non-judgmental documentary focuses on the people who make up around half Wotton's clients, severely disabled men. As the camera delicately pans over incredibly intimate scenes of the parents of one disabled man getting his bed ready for his night with Wotton, it becomes clear just how taboo the sexuality of the disabled actually is.

Wotton, who is presented as having a happy, fulfilling life as a sex worker and activist, sees herself as providing a socially important service and at one point says she hopes to open a non-profit brothel.

Call Me Kuchu (pictured above) tackles another taboo subject, homosexuality in Uganda. Centred on the late David Kato, an LGBT activist who was by his own admission the first openly gay man in the whole of Uganda, the film gives an insight into what it means to be gay in a country where it is illegal.

With fanatical Christians denouncing homosexuality as a sin, a tabloid called Rolling Stone shockingly outs gay people on its front pages, endangering the lives of Kato and his gay friends.

The newspaper's claim that "homos" are in league with the militant Islamic group Al-Shabab would be incredibly funny if it wasn't so dangerous. Watched from a relatively sexually enlightened Britain, Call Me Kuchu is a reminder of how the legal and political system of a nation can be organised to persecute a whole section of society. As Martin Luther King once said, "Never forget that everything Hitler did in Germany was legal."

When it comes to climate change and the environment it is West, and particularly the United States, that is out of step with the rest of the world.

A Fierce Green Fire: The Battle For A Living Planet is a US-centric history of the growing green movement fighting to resist the destruction of our planet.

Key figures and moments of resistance are highlighted, from the Sierra Club's opposition to dam- building in national parks in the early 20th century, to the 1970s Love Canal toxic waste controversy and the direct action of Greenpeace's save the whales campaign.

Inspiring and mainstream in intent, director Mark Kitchell maps the environmental movement's shift from saving wild places to the altogether bigger task of saving human society. The question is, as several of the talking heads ask, is humanity up to the job - and will we act in time?

Sheffield Doc/Fest runs from June 13-17. For full details visit: www.sheffdocfest.com