Famed for making home cooking approachable and achievable for millions of people, and for lobbying for better children's public health, Jamie Oliver’s influence doesn’t seem to be wavering – even 20 years on from the Naked Chef first appearing on our TVs.

His restaurant chain may have recently gone into administration in the UK, but a few months on, he’s "moving on, dusting down" after a "very, very painful" time and focusing on his next venture – and this time it’s plant-based.

So is the man who brought us the 'insanity burger’ turning off meat altogether? "No. No way, Jose!" he quaffs, and although a self-confessed meat-lover, it might surprise you to learn that he eats meat "probably only twice a week" these days.

His new Channel 4 show Meat-Free Meals and cookbook Veg feel bang on the zeitgeist. It’s no coincidence that social consciousness around food is changing; we all know that cutting down on meat is better for the environment, as well as for ourselves.

"Yes it’s trendy at the moment, that’s cool," Oliver, 44, says, as if preempting any assumptions that he’s jumping on any bandwagons. He wrote (and shelved) this book eight years ago, in fact. "I could be wrong but I hope that now is the time to go quite hard and mainstream on veg," he says, and in true Jamie Oliver style, he’s determined to normalise it, to get all of us cooking it, all of the time.

"We’ve made it [vegetarianism] more faddy than it needs to be. Veg has been depicted as quite a divisive thing, like football, gangs," he muses. "Vegan, vegetarian, pescatarian – what are you? But it doesn’t really matter how you look at it, humans are absolutely deficient in veg, legumes, and fibre.

"Maybe it’s because I’m a bit older," he adds, "maybe because it’s 20 years down the road, but I hope it feels like: If Jamie Oliver is doing a vegetarian book, it’s sort of saying something [about] where we’re at and where we’re going."

The new TV show sees Oliver travel to countries where veg is often front and centre of the cuisine, like India and Israel. "Meat has always been an expression of progress, it’s always been a luxury or a sense of cash or commerce – but when you haven’t got much of it, humans are beyond genius," he says, on the food he discovered travelling. "The diversity of textures and colours, for really affordable – onions, carrots – everyday things like pickles and fritters, things that give you the same hugging feeling as a burger or a pizza. You’re kind of sitting there going, ‘I don’t want any [meat], I’m really happy’."

He even visits a meat-free school: "The idea of schools going veggie is a brilliant idea – it would save loads of money."

Oliver says he wanted to go back to focusing on "Monday to Thursday eating, busy working people" for his Veg cookbook (which is incidentally 30-40% vegan), and it certainly harks back to the style of 30-Minute Meals and 5-Ingredients.

It’s not rabbit food though. "It’s a celebration, not commiseration," says Oliver. There’s heartiness (crispy cauliflower katsu), comfort food (Indian-style chip butty), nutrient-dense (veg tagine) and naughtiness (cheesy kimchi toastie) and ‘Friday night nibbles’ for the end of the week. "For me, it’s a relief! I’ll pour myself a little whiskey maybe and I want to have something fun to nibble on," Oliver says of his Friday nights.

"It’s about making it simple, delicious and as good as it can be, I’m not trying to give you the best," he adds, ever the realist. "I’m trying to write recipes that are car crash-proof; OK so you chopped it really badly – that’s cool, chop it badly."

He doesn’t want busy people to open the book and think: "‘Well I’m never going to do that, not until the weekend’."

It’s why he’s a big fan of using frozen food, particularly veg. "Frozen is the future," Oliver declares. "The science of freezing has never changed, it’s just that we’ve always frozen a lot of s***. The chances are that your frozen pea will be more nutritious, and in better condition, than your fresh pea that’s been sitting in a warehouse for a week.

"If you care about higher welfare, cheaper price – frozen. If you care about lack of waste – frozen. Convenience, portion control, nutrition – frozen."

In recent years, Oliver’s recipes haven’t been without controversy though; he was once criticised for using chorizo in a paella and last year ‘Jamie’s jollof rice’ attracted thousands of comments, many claiming he was ‘appropriating’ a traditional West African dish.

"I just think that food can be political, it can be divisive," he says. "I learned to make the best hummus I’ve ever had from theoretically one of the best hummus makers on the planet – and there was at least 300-400 comments that went really dark and really political. We were in the West Bank, Israel, so you’ve got to be really careful."

Politically speaking, Oliver has never been one to shy away; is he planning to lobby new Prime Minister Boris Johnson on child public health? "Always!" he declares – and there’s a long list apparently. "I’ve met him on a number of occasions, I’ve seen him as mayor, I’ve seen him say one thing and contradict one thing, but what now? Will we continue to weekly speak to his teams? Yes. Will I want to meet with him as soon as possible? Yes. Is child health a central pillar of Britain now and in the future? Yes.

"The biggest morally wrong thing we have to deal with right now is that too many times, the better or healthier option is too expensive. We definitely need governments around the world to subsidy better food.

"Generally, what a child and what a family needs is the same as what the planet needs –  more veg, more nuts, more seeds, more legumes. If I had a magic wand, I’d love to go to David Attenborough and say, ‘Can we do a show called My Health, My Planet?’ Because I think that’s the conversation now."

I think it’s safe to assume we’d all watch that.

Meat-Free Meals airs on Channel 4 this September. Veg by Jamie Oliver, photography by David Loftus and Paul Stuart, is published by Penguin Random House.