Legendary director Ken Loach has returned to helm I, Daniel Blake, a stinging indictment of the benefits system set in Newcastle, which scooped the top prize at Cannes. He talks to Kate Whiting about the inspiration behind the film, and why it's up to his wife if he makes any more

Ken Loach is a man on a mission: to get people questioning the world they live in. In his latest film, I, Daniel Blake, which won the prestigious Palme d'Or at the Cannes Film Festival in May, there's a scene set in a food bank, while outside there's a queue of real people who have all used them.

It begs the question, when you pop a packet of biscuits into a collection box, do you ever ask yourself why food banks exist and where those cookies will end up? Or do you take it for granted we're now a country that relies on charity donations, rather than the state, to feed its poor?

"The rise of food banks is intolerable, it's completely unacceptable," says the softly-spoken director, who turned 80 in June. "There were 1.1 million food parcels handed out last year, and over 400,000 of them were to feed children. Nearly half a million children eating through charity."

In I, Daniel Blake, the eponymous hero (played by Dave Johns) is 59 and has worked as a joiner in Newcastle for most of his life. After a heart attack and nearly falling from scaffolding, he's deemed unfit to work and has to turn to state benefits for the first time. It's a film with heart and humour, but one that paints a bleak picture of life for those who fall between the cracks in our benefits system.

It was largely reported that Loach's 2014 film, Jimmy's Hall, was intended as his last - but that he felt so strongly about I, Daniel Blake, that he came out of retirement. While that may not be quite true, there were compelling reasons behind his decision to team up with writer Paul Laverty again.

"Paul and I talk all the time and exchange ideas, and we were both watching out for the same stories about how the social security system was being undermined and changed and used to humiliate people, so we thought we'd investigate it. We went round to six or seven cities across England and the same story cropped up. The very first day we met, we went to my hometown [Nuneaton] and there's a charity I've got a little connection to, who introduced us to a few people.

"The first guy we met was a young man, who's 19. He'd got a housing benefit and he was trying to work. He was doing a few odd days, bit of work on the black economy, few quid in his hand now and then.

"We went to his room, he'd got a mattress on the floor and a fridge. Paul said, 'Do you mind showing us what's in the fridge?' He opened the door and there was nothing in the fridge. Paul said, 'Do you ever get hungry?' And he said, 'Yeah'. The week before, he hadn't eaten for three days. And that's a normal 19-year-old lad. He'd obviously had trouble at home and had split from whatever family he had, but he was ready to work. That was the first day, we just heard story after story like that."

At the film's London premiere the night before we meet, there was a group who'd made a banner showing pictures of people who'd died while stuck in the benefits system.

"They say their death is linked to the fact they'd been sanctioned and had no money, people committing suicide," says Loach.

Also present at the 'people's premiere' was Jeremy Corbyn, who Loach has known "for years".

In fact, the film-maker sees the beleaguered Labour leader as the answer to much of the mess we've found ourselves in.

"It seems to me the only way through the morass is a Labour party led by Jeremy Corbyn - they would end the assessments and re-examine the whole sanctions issue," says Loach. "But more particularly, there would be public investment in jobs, in real industrial jobs, in the areas that are blighted like the North East and other parts of the country where the jobs have gone.

"Everybody's got to make a contribution and everyone's got to get a proper wage for it that they can live on, get a house with it, bring a family up and live in dignity like they used to. Everything else is a palliative.

"Certainly, Labour under Blair and Brown had no plan for that, they allowed the areas to rot. Business won't go there unless they can make a profit out of a vulnerable workforce on zero hours' contracts and agency work that you can turn on and off like a tap."

It's been almost exactly 50 years since Loach's seminal 'social realist' drama Cathy Come Home, a tale of one family's descent into poverty, was first shown on BBC One.

Watched by 12 million people - a quarter of the British population at the time - it stunned viewers, as issues such as homelessness and unemployment had never really been discussed before. Such was its impact, the charity Crisis was set up the following year.

Loach has said he "prefers the days of Cathy" when the world was "more congenial, with a stronger sense of social responsibility".

He and his wife, Lesley, have 10 grandchildren ("nearly a football team") - and he admits he worries for their future.

"With 10, it's very hard to see how everyone will get through unscathed. Whether they'll all find jobs and somewhere to live, and all do what you'd hope they would do. It's very hard to imagine.

"Inevitably, they're forced into this competitive thing of trying to get the best exams, because that's the world they're in. But it's not the only way to succeed. Some may be lovely people, but they may not be great at exams, so they will then suffer and why should they? Everyone's got a place and a contribution, and you want to cherish everybody.

"We can't say, 'Every child should be treated equally', and then keep a divisive education system and large areas with nothing for anybody to do."

Loach would like people who watch I, Daniel Blake to "see the world through his eyes" and then ask "the big questions", like: "Why are we living like this? Why are the Government behaving like this?"

As for what's next, he's not sure there will be another film.

"Paul and I are talking about stuff all the time, but whether I'll be able to do another... My missus gets fed up with me being away all the time, I don't know if I'll get another one done," says Loach.

"I'll have to wait and see."

I, Daniel Blake is in cinemas now