KEN LOACH is unexpectedly mild-mannered for one of Britain’s most polemical film-makers. The 76-year-old left-wing director of award-winning films such as "The Wind That Shakes the Barley" about the Irish fight for independence, discusses his latest documentary, about post-war Britain, with a quiet, measured confidence.

"The Spirit of ’45" is an unreservedly nostalgic look at the nationalisation of British industry, including the railways and the health service, following the landslide election victory of Clement Atlee’s Labour party in 1945. Made up of archive footage and contemporary interviews with Brits who experienced this post-war transition, it is not so much about the politics, says Mr Loach, but about a time of hope.

Mr Loach spoke to The Economist about socialism, rummaging through archives and the trouble with commissioning at the BBC.

How important was your choice of title?

The title is very specific. The film isn’t a detailed analysis of the politics, it’s about the mood. People had been through the depression of the 1930s and the huge struggle of war. They were hopeful but such a collective experience had left them with very strong feelings about what they wanted to happen next. One of my favourite bits of archive footage is when Winston Churchill [Britain’s prime minister before Atlee] is heckled. He’s a sanctified figure now, so to see what the working classes really thought of him in 1945 is very salutary.

You have made films about these issues before: homelessness in “Cathy Come Home”; the railways in “The Navigators”. Is this film the culmination of your other works? Why now?

It's something I'd thought about for a long time because I think those few years after the end of the war have been largely written out of history. It is in no one's interests to remember that time, certainly not the Tories or the Liberals or even New Labour—they’re committed to market economics. I suppose there is a current relevance in the partial privatisation of the National Health Service, but mostly I just wanted to do the film while the people involved are still with us. Their memories are a resource.

Have you enjoyed returning to documentary film-making?

It’s good because you don’t get so cold! You get to look at archives for hours in the cutting room, which means you don’t spend as much time standing on windy street corners.

Was there anything that didn’t make the final edit?

We talked to some young people, students interested in politics. We showed them the 1945 Labour Party manifesto. Many said this is what we need now, things like libraries, concert halls being made available to all, at a time when we’re closing arts venues. It was fascinating. But I found that in order to do justice to their contribution you’d have to extend the film and interview more people than we had time for.

Are you advocating renationalisation?

You have to question whether the current system is working, and it plainly isn’t. So yes, maybe we should consider communal ownership, a planned socialist economy.

Would you describe yourself as a socialist?

If the word hadn’t been so roundly abused.

Do you think this film about British politics will travel well, to America for example?

I don't know. There are very strong trade unions in the United States. You just don’t hear them. The film went to the Berlin Film Festival and we certainly got a very warm response there.

Do you see yourself as a journalist or an artist?

I wouldn’t draw that distinction. A journalist uses the most precise words he or she can. An artist does the same sort of thing. You gather material about a particular subject, you refine it as best you can.

It’s a difficult question, because even someone who writes the news writes it from a particular perspective. Admittedly, when I switch on the news I don’t want to see someone presenting a case in the way that we’ve presented this film. Although it can never achieve it, the news should strive to be objective. Whereas I guess the standpoint I take is slightly different. My perspective isn’t hidden, but I present evidence for that perspective.

Do you think documentaries are a good vehicle for social concerns?

Absolutely, but the documentaries that need to be made tend not to get commissioned or aren’t shown. Because I've been around a long time I get a bit of leeway that other people don’t.

Take the BBC, for example. The problem is not one of finding good film-makers or writers or journalists. The problem is one of commissioning. There's so much control, so many executive producers, so many people looking over their shoulder, so many people trying to second-guess the boss. The space for writers and directors and actors to be creative is zilch.

"The Spirit of '45" will be released in Britain on March 15th 2013