A really very encouraging thing has happened over the past few years. As investment in television documentary has collapsed and the quality of the output on broadcast has followed southwards, a new world of cinema distribution has opened up. Films that no one would have considered marketable ten years ago, now get small but successful runs at art house cinemas across the country. In part this is one of the unintended consequences of the shift away from 35mm to digital - in the past documentary production houses simply could not afford to create the prints required to show in multiple cinemas - the return was too uncertain.
But there's something deeper and more interesting behind this change. Just as nature abhors a vacuum so audiences in super-diverse cities seem hungry for the kinds of stories that only films with one foot in the real world can tell. If the broadcasters wont provide them, people will pay for the experience in the cinema.
As the founding director of London's only festival devoted to exploring the documentary form - Open City Documentary Festival - I've been watching these shifts in the five years since we launched. More, my festival has been lifted by this rising tide of public interest with audiences growing fourfold since we launched enabling us to offer an ever more ambitious programme of screenings, events and meet-ups.
Above all what this audience demand means is that we are free to program only those films that really set out to work as cinema. A few years back the great Russian filmmaker Viktor Kossakovsky laid down Ten Rules for Documentary Filmmaking. His second commandment reads - 'Don't film if you want to say something - just say it or write it. Film only if you want to show something.' It's no different from Spielberg, really - story telling in pictures - but it could stand as our guiding principle too - we choose films that show the world as you've not quite seen it before; films that make you look again, films that don't tell you what to think, but set you thinking.
We also show films that play with the idea of documentary - that explore what happens when you turn a camera on people. Readers of Sight and Sound will know Robert Greene as one of the smartest new voices on the circuit, but he is also an acclaimed filmmaker with a hugely impressive list of credits but which has yet to get the recognition it deserves in the UK. His last film, Fake It So Real, named one of the 15 best films of 2012 by Richard Brody of The New Yorker and one of the best documentaries of the year by Roger Ebert but his work has so far been confined to true documentary cognoscenti.
So this year, we're bringing Robert over for the whole festival and screening his latest movie, Actress - a knowing but kind and generous film about Brandy Burre who had a recurring role on HBO's 'The Wire' until she gave up her career to start a family in upstate New York. Mixing melodrama and cinema verité, Actress is a compelling exploration of a complicated woman, performing the role of herself. Quite who is telling the story here - whose story this is - remains a puzzle throughout.
At the other end of the emotional and moral scale, Of Men and War, takes us to a place where it's hard to feel comfortable. Filmed in a rehabilitation home for US combat troops back from Iraq it asks truly troubling questions about this kind of war and the suffering urban guerilla war imposes on the troops who are sent can't imagine there is anyone who won't have at least one prejudice overturned by this fine, unflinching film.
We are incredibly privileged to be running a festival of this sort in London and we try and give something back to the community that supports us - not just seed funding for one film project a year but through a whole panoply of workshops, meet-ups and networking events. Top of the list for me this year is a day of presentations and hand on play, funded by UCL's Faculty of Engineering, bringing together documentarists with the computer scientists at the forefront of virtual reality simulation.
Virtual Reality has the potential to do something very similar to film - to transport audiences to anywhere they want to go and to places they could never even imagine. Stepping into an alternate reality, VR technology allows users to explore things from a new perspective and the landscape of creators is rich, diverse and changing at a rapid pace.
With three sessions looking at current VR projects, we've invited producers at the forefront of innovation in the worlds of games, film, experiences and art. Projects like Amplified Robot, We are Formation, The Machine to Be Another and Immersiv.ly will be asking how filmmakers should approach building virtual worlds for their audiences if the future of storytelling lies in a headset.
In the week I write this, BBC 2 - once the home of more challenging broadcast - has just announced a sickening attempt to trump Channel 4's Benefits Street with a reality documentary show that mixes Hunger Games with poverty porn. If you need to be reminded what documentary can be, just what marvels true cinematographers can make from the real world - come along and join the fun in venues across the centre of London!
The 5th Open City Documentary Festival runs 16 - 21 June, see http://opencitylondon.com/programme/films