TV chef James Martin on his epic road trip around the British Isles

When it comes to TV chefs, there are only a few who've been chopping, frying and serving up dishes on our screens for more than 25 years - and James Martin, with his straight-talking, homely and down-to-earth manner, is one of them.

Cookery programmes have been a mainstay since Philip Harben showed BBC viewers how to make lobster vol-au-vents back in the 1940s, but even before Jamie Oliver and Nigella Lawson shot to fame in late-Nineties, Yorkshireman Martin was already a familiar face on telly, and has been ever since.

Following his popular foodie road-trips around France and America, the chef – who trained at Chewton Glen in the New Forest – is back with a new cookbook (his 23rd, he says), James Martin's Great British Adventure.

Now is an important time to really embrace British food, says the chef, admitting this was one of the "fundamental reasons" for wanting to do the book (and its accompanying ITV series) in the first place.

"I'm a farmer, and this is an amazing country we live in. There are some amazing people producing some amazing food - whether they cook it, serve it, make it, or brew it," Martin enthuses.

Like a love letter to Britain and its food, James Martin's Great British Adventure takes home cooks on a journey the entire length and breadth of the land - from the Isle of Wight for feta and halloumi and Wales for the beef and lamb, to Northern Island for langoustines and Scotland for "the best fruit in the world", along with many other gems in-between.

He's almost overflowing with stories of fascinating people and underrated produce from his exploration of the British Isles. There's the vinegar producer in the Orkneys who set up his business in his dad's garage, a breed of acorn-fed hairy pig called Mangalitsa in the New Forest - and another, Middle White, farmed on the Wales-Gloucestershire border. "It's the best pork you'll ever taste, and used to be really famous in the Thirties but now we all want pigs to look like they've done 100-metre hurdles, with no fat on them, but that's where the flavour is," says Martin.

"There are 200 Middle White sows in the world and this guy has got 100 of them - they're rarer than the king panda" - but only because we don't buy their meat. "People are creatures of habit," Martin adds.

British cuisine, with its modern multicultural power, is finally having its moment in the spotlight. "Thirty years ago, we were deemed as the poor cousin around the world in terms of food, but in France I met some of the greatest chefs in the world, and their attitude towards British food and British chefs is totally different. Now we're on a level playing field, if not better - they see London as the gastronomic capital."

Famed for recipes that don't overcomplicate for the sake of it, long-standing Martin fans will be be pleased to know that his latest collection stays true to that approach. "I'm still off the ethos that you should never cook anything on TV that my mum can't get north of Watford," he says. "I think chefs can go too restauranty and you'll start to lose people." And although he takes some inspiration from British classics and age-old techniques, "it's fundamentally about the place, about the ingredients, about now", he adds.

It's been a long time since Martin first did work experience, aged 14, in a London kitchen, at the Park Lane Hotel - and longevity, in a world of Instagram foodies and YouTuber cooks, is not to be sniffed at. "This book is an accumulation of 35 years of work, of knowledge, built up over the years," he says. "And that knowledge, you can't buy it and you can't Instagram it."

James Martin's Great British Adventure: A Celebration Of Great British Food With 80 Fabulous Recipes by James Martin is published by Quadrille, priced £25. Available now.