Tell us about the new run of Grand Designs, opening with the Irish castle.

It was a really interesting project to follow. I was in two minds about it because we had a project that had very little in the way of drawings, not a clear vision, and it didn’t seem to be exemplary as a conservation project. But it was mad and out there, and the guy doing it is completely loveable, and the setting is utterly romantic and beautiful. It’s an extraordinary tale of connection to place and connection to this landscape and to memory.

It’s an unfinished project, so at least there’s a chance to revisit it.

I don’t like to finish a series with unfinished projects. I think it cheats the viewers; I think people sitting through an hour of television want to see the resolution. They want to know that it’s been worth it. It’s just unfortunate. The channel has a slot, we have to fill that slot and sometimes the projects aren’t finished.

Are there any outlandish designs in this run?

Oh yeah. Do you know what? I welcome the recession. Not with open arms, but I welcome aspects of it inasmuch as money is no longer freely available. People have to be more cautious, but they are more inventive, and far more ingenious because they have to be. You used to have to write a cheque to get out of a hole. You can’t do that now. You have to think your way out of a hole, and that’s good for the design, good for the project. I get a hunch this is the strongest series we’ve ever produced because of that.

Tell us about some of the other builds and renovations.

We’ve got a really exciting beautiful crystalline set of modernist boxes piled on top of each other. It’s a very minimal interior in concrete. We’ve got an amazing water tower in south London, 100ft high, the likes of which has never been filmed before, and that is part conservation job and part new build. We’ve got two ladies living in Hertfordshire who place all their money and faith in a group of young designers with a building system using boxes of wood that has never been tried out on this scale before ever. It involves basically a router in a shipping container delivered to site, and the whole building is cut and mounted out of sheets of plywood; cassette boxes almost, and that was wonderful to witness.

Grand Designs Live is a huge international hit. What can you tell us about the latest shows?

We’re in Birmingham in October. Prior to that there’s one in Australia. It just goes around the world. I think there’s one in South Africa as well. I think we’re in 145 countries now. Where there are countries where the series is strong, we have an exhibition as well.

How has the Live show changed in Birmingham over the years?

We’re used to getting a different kind of visitor now; they are less interested in shopping and more thoughtful and more interested in projects. It’s much more like the show we have at Excel in London. So, for example, this year I’m doing slightly less on stage and I’m doing a bit more in the Ask The Expert room, where you turn up and can get a free consultation with architects and designers. That’s a wonderful part of what we do, Ask The Experts. No one else offers this where you turn up and get free advice, and everyone gives their time for free. The architects, the designers, the engineers, the surveyors, the mortgage company experts, all coming and giving advice on a one-to-one basis. The other thing we’re doing is launching a new initiative. It’s a retrofitting scheme called Grand Designs Future Living, and it will give people the opportunity to take advantage of the new deal coming out in the spring to retrofit their homes with all kinds of insulation and all kinds of clever technologies. I’ve also got a book coming out called The Best of Grand Designs. It’s celebrating the fact that we hit our 100th episode this autumn.

Tell us about your other upcoming series, Man Made Home.

That was partly inspired by reading Roger Deakin’s book about the natural world, but also it was about trying to provide myself with a little bolt hole for some low impact, low carbon living for the weekend.

Finally, would you ever like to do a movie version of Grand Designs, discussing projects such as James Bond movies and the Harry Potter films?

What a great idea! We could do the Kubrick sets of 2001; ancient Rome in Gladiator; Hitchcock’s settings - there’s that wonderful 1950s architecture in North By Northwest, and Portmeirion in The Prisoner. I’ll do it as long as you don’t want to charge me a royalty !

Kevin McCloud presents the new run of Grand Design Wednesdays, on Channel 4.