From politics to broadcasting, Michael Portillo has enjoyed quite the successful career change. As he sets off on another railway adventure, he tells Gemma Dunn why he's more than happy to be on this side of the tracks.

Michael Portillo is partial to a plucky blazer or two.

Those who have seen the politician-turned-broadcaster in action on Great British Railway Journeys will have seen his clashing combos become a series staple - a "standing joke" that has grown with the show.

And the more flamboyant the better, he has said previously: "For it has a couple of advantages as far as TV is concerned: one is you're bright and joyful at the beginning of a show; and the other is that in a long shot I'll be the only person dressed in a shiny pink jacket on the bridge, so you can see where I am!"

"It's funny that you should mention this... I spent part of this morning with my tailor planning new jackets for next year!" Portillo, 66, chuckles now, when we speak on the phone.

"Normally I get two or three new ones a year, so there's not a total turnover - viewers will be able to see old favourites from several years ago no doubt - but the stock is refreshed!

"And then of course there has to be new accessories, new shirts, new trousers, new socks, new pocket handkerchiefs, new nightshirts..." he tails off.

It's been 15 years since the Hertfordshire-born star left politics behind.

The successful minister - who has served on everything from transport to employment to defence - announced he would stand down in 2005, by which time he had already built up a portfolio of media work.

Since then, Portillo has transformed himself from a once stressed (his own words) politician to that of a popular presenter, fronting everything from straight history in Hidden History Of Britain to documentaries and beyond.

"I don't look back [at my political career] with any sense of nostalgia," he insists. "I've been lucky because there are vast numbers of former politicians - mountain loads - who I expect would each like to spend his or her second career in television, but not many of us have got to do it!

"So I've enjoyed both halves of my career very much indeed."

The latter half has seen him travel the globe, with Great British Railway Journeys - now on its 11th season - extending its travel documentary format to other territories including America, India, Australia and Canada.

Now Portillo is set to embark on another adventure in Great Asian Railway Journeys, taking in the likes of Hong Kong, Thailand, Vietnam, Indonesia, Malaysia and Singapore over a 20-episode run that will see him explore everywhere from towering megacities to magnificent mosques.

"I've been keen to take the series somewhere new each year," he reasons of the spectacular 2,500-mile journey, undertaken with his 1913 Bradshaw's Handbook.

"The basic elements are the same: we're travelling by train, but we're uncovering history," he continues. "In these parts, we're talking mainly about colonial history - not just British colonial history, but European colonial history in general. So we talk about the Dutch, the French, the British and, to some extent, the Portuguese.

"I was looking forward to going to Vietnam because being of my generation that remembers the Vietnam War, it still seems extraordinary that you can go to Vietnam as a tourist," he muses. "And that when you get there, the Vietnamese people are so generous after a war that was so destructive."

Beginning in Hong Kong, Portillo will investigate how Britain won the island and Kowloon from China after two shocking drug wars; plus straddle a bamboo pole to learn the traditional Cantonese art of noodle making. Really.

"It was amazing to find a little flat covered in flour dust, where these noodles are being made!" he chirps. "But even more extraordinary to discover this in Hong Kong, because most people's impression is that it's thoroughly modern and maybe even clinical. But Hong Kong was full of surprises!"

What else did he do to immerse himself in the local culture?

"In Thailand I did Muay Thai, [where] you use four parts of the body: feet, knees, elbows and hands - fists," he explains. "But the first thing you learn is how to punch, and the way in which [the master] gets me to do that is he wants me to pretend that my arm is a cobra.

"So if you imagine the speed at which a cobra leaps forward, that's my arm tearing into my opponent!"

It's a full-on schedule - seven-to-eight weeks, in fact, filmed in two legs. Not that Portillo is complaining.

"The material we're dealing with is so stimulating [that] you get up every morning really enthusiastic to do the day's work!" he notes.

"We have time to think through plans we want to make and to draw the arguments out from people that we're talking to," he adds. "But in any case, I'm one of these people who believe you produce your best work when time is short and you're under quite a lot of pressure."

Do the trips impact the way he lives back at home?

"I really was very ignorant about all of these places, but even if I hadn't been, when you go there, the perspective is completely different," he admits.

He follows: "In Kuala Lumpur, Jakarta, Singapore or Hong Kong, people live at the same lunatic pace that we do in London, but we're showing that close by, there's still a very traditional way of life.

"I think the 21st century is going to belong to Asia; there's such a lot of activity, development and so much infrastructure, such energy, so much education, it's a very dynamic place," he concludes. "I felt a sense of passing the baton, if you like, from the older world to this one."

And where to next?

"Later in the year, we've got a series in Europe," he details. "[As for further afield], what we need to determine where we go is referenced in our Bradshaw's Guide and sufficient railway infrastructure to get around.

"If you go to China and Japan, to name places that I would like to go in the future, because of high-speed trains you can cover huge amounts of distance without taking up a lot of the schedule... on trains!

"A lot of people, just because of the title, think the programmes are about trains - they're not!" Portillo is keen to point out. "They're about history and they're about culture: the train is our vehicle.

"So I say, 'No, it's not about being on trains, it's about getting off trains'," he finishes.

Great Asian Railway Journeys starts on BBC Two on Monday.