How The Light Gets In is a thought-provoking mix of philosophical debate, music, and comedy.

Started over a decade ago in Hay-on-Wye, the festival moved to Kenwood House a few years ago and takes place this year on September 17 and 18 with music from the likes of Mercury nominees Gwenno and Django Django; comedy from Tatty McLeod, Ahir Shah, and Alfie Brown; and cabaret from Bourgeois & Maurice.

But the main event are the speakers and thinkers who are "changing the world" including Nobel and Pulitzer prizewinners.

Hampstead playwright David Hare, Highgate novelist Esther Freud, "the godfather of altruism" Peter Singer, and radical director Sophie Fiennes are among those lined up alongside string theorists, politicians, think tank directors, historians, cosmologists and neuroscientists.

The festival's director, philosopher Hilary Lawson, says it grew out of his Institute of Art and Ideas.

"There was no grand plan when we started but it has grown through enthusiasm for what we were putting on.

"We try to create an atmosphere that is engaging, beautiful and exciting. London is very obsessed with status, but we've tried to get away from that in the festival. We don't have VIP areas and try to get everyone to mix, so you may well be standing next to a Nobel prizewinner in the coffee queue and get into conversation. Kenwood is a very beautiful location that enables you to escape from the city, which helps everyone's frame of mind."

Speakers he says, are "world class in their field" and the conversations "at the cutting edge".

"If you want to know what's going on these are the people to listen to. We're not encouraging them to dumb down. The debates are the key things that people are trying to address at the moment. You don't have to be an expert in cosmology or string theory to have a sense of what's at stake by listening to their positions and getting a grip of what's involved."

With its complex ideas and deep thinking, the festival is the opposite of the Fomo driven gnat-like attention spans of the social media age.

"The way we interact now encourages short gobbets of information and opinion which is counter to having any serious thought about where we might be going - but more and more people are not happy and find that unsatisfying.

"We were a bit concerned that people would drop in with something more interesting to do somewhere else and not be quite present. The point is you have time to discover things that you wouldn't otherwise discover, or hadn't decided to find - you happen to be chatting to a key scientist or philosopher and think 'I am going to stay for this'."

He hopes the institute and festival have helped to change the culture around big ideas in the UK and US.

"The initial motivation was because philosophy was a bit of a joke, something we should leave to Parisian taxi drivers, and The Academy had got lost in a linguistic thicket, turning it into a technical subject, arguing about words which didn't have much bearing on people's lives. It seemed rather ridiculous that we can't really talk about the big ideas that we all have to address. I hope we have in a little way changed the perception of philosophy and it's not quite the joke it was."

For him, philosophy is "the big ideas that drive our lives".

"Everyone is a philosopher in the sense that being alive is an extraordinary thing and, like it or not, you have to come to terms with big questions like who you are, and why are we here Everyone has to engage with those questions. We should be discussing what we should do about them and addressing the many challenges we face."

He is loathe to pick out highlights from the 2022 line up, but cites neuroscientist Iain McGilchrist as "always challenging on how the brain works," and is looking forward to sessions with David Hare, Labour politician Thangam Debbonaire and director Sophie Fiennes, as well as debates on The Key to Consciousness and The Fantasies of the West.

But he says: "The thing that drives us are the ideas in the debate. We don't start with celebrity names but with the idea."