Kevin McCloud looks suntanned and is full of stories about his latest trip abroad. But, on closer inspection, the tan is more weathered than brassy and the stories are something verging on life-changing rather than the usual anecdotes from far-flung shores.
He has just come back from spending time in India's notorious Dharavi slum, which sprawls over Mumbai and was given the big screen treatment in Danny Boyle's multi- Oscar-winning movie Slumdog Millionaire.
Those who have grown accustomed to seeing McCloud (50) surrounded by the manicured lawns and gazebos of Grand Designs are in for a surprise watching Kevin McCloud: Slumming It, his latest TV documentary.
Most surprised is McCloud himself who says that he was lost for words for the first week of his time there, experiencing slum life by being put right into the thick of it.
He says: "I saw this great sea of rubbish, like a municipal dump, and I realised camouflaged among the rubbish were tarpaulins, and underneath them were people -- it was like a hobbit world -- and then I realised that they lived there.
"I was completely aghast. I couldn't do my job, I stood there and my jaw dropped and I couldn't say anything for about five minutes and it was like this for a lot of the first week. "
The mission was to find out about the everyday workings of the slum, in which about a million people live and work, to see if there were lessons to be learned about town planning and architecture.
The slum has been held up as an example by town planners and even the Prince of Wales who praised its community spirit and sustainable living.
Architecture enthusiast McCloud was not as impressed. "I think he's being very hopeful. The part in which they make pottery, for example, they're entirely dependent on one product they make and they live by very polluting kilns. I'm afraid if the market changes and nobody wants pots anymore, they're stuffed. I don't see that as a flexible community at all."
Father-of-four McCloud should know about the pottery community -- as he lived there while filming the programme, sharing the floor of a small room with four other people.
He explains: "I managed to sleep there right up until the night when all four people were asleep snoring, and I heard this rustling, and it was really loud, and I turned a torch, on and there were bloody rats everywhere!"
He also travelled on a dump truck to find out about rubbish and recycling collection and, shockingly, once came across a dead body in the road.
"Frankly, life is cheap there," he observes, adding that the main problem is minimal healthcare education.
But surely, in the end, it was a useful trip for McCloud as well as an eye-opening one?
"I gathered lots of small ideas about how people live, but I have to say the big problems which I keep on coming back to are sanitation and healthcare. Clean drinking water is so fundamental, and it's not being addressed.
"Any attempt to eradicate slum living is futile, what we need to do is think of ways we can help to make it better."
It's clear that McCloud is on a mission and that his questions will take a lot longer to answer than any of his Grand Designs projects have ever taken to finish.
In the meantime, he's busy working on a new series of the building show, which he says is even more exciting than ever, with "wilder and more unusual" projects.
With each new series we push the boundaries a bit more," he says.
Kevin McCloud: Slumming It is on Channel 4 on Thursday January 14 at 9pm