Your first book documents a debate between Leibniz and Clarke – not the most obvious chef’s primer!

This book’s about the death of mysticism, and it was the book that killed anything like that in me. I’m an atheist; I don’t believe in star signs or luck.

What form does the book take?

It’s a discussion between Leibniz, who was a philosopher and mathematician, and Samuel Clarke, the philosopher, scientist and champion of Isaac Newton. Leibniz was defending a position that suggested we had no free will at all. He was trying to reconcile the experience we have of free will with God’s omnipotence, and in order to do it he suggested that we have no ability to test our own experience, that we exist in complete isolation from each other and the world. Clarke just comes back very pragmatically: common sense questions, and I found that every time Clarke was talking I was going, ‘absolutely right, quite right’. And I ended up feeling that while there was fun to be had in the Leibnizian point of view, life is just too short…

Back to food.

People will talk about flavours relating to one another according to season or whatever, but I want to ask, if lemon juice, from a summer fruit, is doing a particular job, supplying a bit of bite, a bit of acid in a dish, can I do that with something else, like vinegar? What’s wrong with that? Another chemical that has the same effect?  I don’t say conventional wisdom’s all bad; there’s plenty of good eating advice in the Bible. But you should be able to unpack it, question it and push the boundaries a bit further.

Let’s move on to your second book.

This is the one that first got me really excited about food: Down and Out in Paris and London, by George Orwell. It’s meant to be the book that shows you everything that’s wrong in hotels and restaurants. A young Orwell goes to a hotel and then, I think, a Russian restaurant in Paris, and works like a slave. It’s the most chaotic, poorly paid job, with people living to drink their wages at the weekend, but it was the first thing that really excited me: the idea of the production of restaurants, the front and the back.

Like a theatre?

Yes - you’re putting on a show every day. Every service is a show. And I like the idea of the back of house, the machinery, making this whole thing work for the front of house. My first job was as a chef in a hotel restaurant on London’s Park Lane, and it was incredibly grand. But you went back of house and between your shifts you’d go down to the staff room in the basement with no natural light, and everybody smoked down there. There were smashed-up hotel chairs and a TV that played news all the time, and snoring porters and chefs in their whites grabbing a couple of hours’ sleep, and I found that exciting: the upstairs/downstairs thing. That you go upstairs from there and put on a show. It’s a bit like one of those Heath Robinson drawings – it’s fun to see how each thing fits in with another. Having said that, I like to think that the working environment at Leon is slightly more fun for the people who work with us.

What about your third book, the Pépin?

At that stage, when I was working in the hotel, I asked what book I should read to learn about cooking, and I was given La Technique, which is a classic French textbook with all the old techniques in it. It’s incredibly dated, but I like it because it displays very clearly the steps that go into creating the finished product, with these very old-fashioned black-and-white photographs for every dish. The chicken liver pâté recipe is still the one I use. Absolutely brilliant recipes, wonderful sauces. But you’ll also have what was considered at the time part of the canon: how, for example, to build a pigeon out of fruit – mad stuff. Jacques Pépin has these very, very hairy forearms, which are in all the pictures... I cook from it a lot at home, and, again, for me it was the beginning of thinking about the wonderful end product and the steps that went into creating it.

How does this all lead to your enthusiasm for fast food?

I was talking to an old friend who’s a restaurateur the other day, and he was saying that, years and years before I set up Leon, I’d talked about setting up a fast food restaurant.