He is a great person to interview: willing to be probed, generous with his time and thoughts, honest, amused at himself. He said he was shy, the sort of man who stands at cocktail parties observing other people. 'But not in a suffering way. When I was at school nobody really noticed me and my parents were advised that I shouldn't even think of going to university. Now I really enjoy public speaking, but I could give a lecture to a thousand people and then find it difficult to talk to two of them afterwards.' Yet his work, which is almost always urban, means he is constantly having to justify himself to public committees. In the same way, he suffers from vertigo, yet designs a building on a peak; he hates flying but commutes regularly to Asia. He had bad eczema until he was in his late 20s and he used to be claustrophobic.

'I think most of my anxieties are a result of self-imposed exposure to those anxieties. If I hadn't pressed myself to be ambitious, I would never have got vertigo or claustrophobia. I could have gone through life perfectly happy.' So is he happy now? He laughed, warily. 'That's a good question. Are you?' Yes, I said, most of the time. I pointed to a news story about the tidal wave devastation in Papua New Guinea and said that was real unhappiness and he suddenly leaned forward and asked, urgently, 'Did it affect the Renzo Piano building? I know he built one around there.' This, though tasteless, was surely the classic architect's question. 'Course it is. People undervalue buildings. When I watch World War II films, it makes me wince when I see all those bombs flying. Thirty Wren churches, 30, were lost during the war, and all those beautiful medieval cities in Germany. I know people were dying too but I can only think of the buildings.' Does that make him, as the product of an Irish Catholic background, feel guilty? He grimaced. 'I'm so anti-Catholic in my old age. My children [he has five] feel neither here nor there about it but when they ask me, I say that, basically, Catholicism is evil.' Yet he has a reputation for being a moral architect: one committee in London accused him of sounding like an Old Testament prophet for banging on about giving the public access to royal parks. He has also claimed that he'd liked to demolish the walls of the palaces ('Like Buckingham Palace, what does it do?') in London.

There is something touching, not to mention metaphoric, about this because he seems to see himself continuously excluded by walls. Coming from a working-class background, he said he had never felt one of the in-crowd. 'I do buildings with a popularist feel, I don't play the taste game. The architects who get on neuter their own architecture to supply depersonalised good taste. There is an incredibly intense clique but I deliberately didn't join.' He paused, pondering that decision. 'As a Catholic, I felt an outsider. Then I rejected Catholicism, so where did that leave me? I feel there was a loss in not joining, a loss in opportunities. And maybe in comradeship. But then, when I do meet other architects, I think, 'Do I want to be friends with these people?' ' Architecture, however, is all he's ever wanted to do. 'At 16, I went to an architect's office for the summer and could hardly believe that there was a better way to spend one's life.' A little later, he added, 'It's still an old man's business ... at least I hope so. I feel terribly unfulfilled, I tell you. I've never done what I wanted to do in London. It's been quite difficult there for the past 10 years. I had tremendous success very quickly and then the expression used was, 'Terry, you've had your turn.' ' I was curious to know how, given his love of designing buildings with personality, he managed to get to grips with the MI6 project. 'I thought it was for the Department of the Environment! I found out what it really was in an anonymous hotel room in Tokyo when I couldn't sleep, switched on the television and there it was. I almost fell out of bed.' Did he mind? 'What I felt disappointed about was that people have taken against that building because it's MI6. People use words like 'Stalinesque' but if it had been the headquarters of Disney or Richard Branson, they'd have read other things into it. I designed something with splendour.' Is he bitter? 'Somebody asked me that the other day. I think bitterness is part of any experience if you're passionate. There are things I'm bitter about but I'm not a bitter person ... I don't find it easy being continuously challenged, it's like being on the edge all the time. Like stage fright. My 14-year-old daughter is terribly insightful - she says that she has her father's mind and her mother's looks and what she means is that she sees things my way - and one day she said, 'I'm so competitive that I can't compete.' And I suffer from that too. If you want to do something really well, the anxiety comes from that.' As for references to the flying wok, he said: 'I actually like people reading into buildings things that are tangible, visually graphic images like that. The worst thing anyone can say is, 'What building? I don't think I noticed it.' '