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After making his name with projects such as the hefty development over Charing Cross Station and the Edinburgh International Conference Centre, Farrell experienced something of a lull during the 1990s. Now he is receiving big commissions again – most notably the masterplan for the area around the Millennium Dome in Greenwich. The flak was in response to proposals to tear down the walls of Buckingham Palace, which he presented in a Channel 4 documentary just after the new year.

Farrell grins mischievously when he discusses the furore over his proposals for the palace. Some have even accused him of offending the Queen. "A couple of Telegraph-reader colonels have written to me, telling me that I'm a disgrace and should return my knighthood," he says. But he doesn't think the Queen really cares about the ideas some architect has for a building she stays in for three weeks a year.

Nevertheless, Farrell vehemently defends his idea of a plaza at the front of the palace. He claims that if he had not come forward, the mishmash of bodies with authority over it would be too scared to commission a masterplanner to rethink how it works.

Knocking down the walls of Buck House is a typical Farrell idea. He takes pleasure in causing a stir – which is just as well after some of the reactions he received to his MI6 building at Vauxhall Cross in south-west London (described as "an awful hotchpotch" in one of ºÃÉ«ÏÈÉúTV's Wonders and blunders columns). He chuckles: "People either love it or they hate it. Some architects avert their eyes from it, and me, when they walk past."

Farrell considers himself the rebel of the big five of British architecture – Michael Hopkins, Richard Rogers, Norman Foster, and Nicholas Grimshaw make up the rat pack. Rebel or not, all five have been ennobled – Farrell's turn came last year.

Farrell and Grimshaw ran a practice together from almost the moment they stepped out of college until 1980, when they fell out and developed different styles of architecture. Grimshaw moved on to high-tech schemes, such as the Eden project, whereas Farrell took on post-modernism and US-inspired urban design. Farrell admits that there were differences, but the ice may have finally thawed. He says: "I did write to Nick to congratulate him on his knighthood this year, and I got a very nice letter in reply."

Farrell and Grimshaw have rarely crossed swords since the split – they have entered the same competition only a handful of times in more than 20 years. Of the big five, Foster and Rogers are his most frequent competitors: "They don't show you any quarter when you're up against them."

Farrell's contest with Rogers is particularly intense. Some of this is to do with the politics of style: Rogers' striking brand of avant-garde against Farrell's frank populism. But there is a personal edge, too. Farrell was critical of Rogers' designs for the South Bank Centre redevelopment, a project that Farrell was axed from in 1993. Rogers replaced him, but was himself dumped a few years later.

Although Farrell keeps a watchful eye on younger architects coming through – he is particularly impressed by David Chipperfield's Henley Rowing Centre – the old guard are still in control. The "designed by Sir Terry Farrell" label impresses planning committees and is usually good for a dozen or so column inches in the broadsheets – just look at the coverage Farrell's The Deep has received. The £45m aquarium in Hull is due to open next month.

Whether Farrell's name won the battle of the Millennium Dome site is, however, less sure. The government was simply desperate to do something – anything – with the site, and was eager to take up Lend Lease and Quintain Estates' plans. Farrell acknowledges that the government's timing was fortunate. Just before Christmas, the media was less inclined to make a fuss about the decision, which left Farrell, unusually perhaps, free from criticism. Farrell says that his initial draft of the high-density housing masterplan for the site is barely developed, but will be ready by May, when the deal is expected to be signed.

Housing is becoming a more significant element of Farrell's work. In September last year, he was appointed to lead CABE's campaign against conservative housing design.

Over the years a more constant theme has been working overseas, from Portugal to Lebanon. He has a Hong Kong office, and Seoul International airport is among his more celebrated works – but not all his experiences have been good. Farrell's tremendous eyebrows merge and his face turns into a frown as he tells of a scheme in China.

Twice in the past two years, his practice was appointed to design a £100m public building in Guangzhou; twice the project was scrapped. Initially overjoyed that he was to be the first UK architect to make a breakthrough in mainland China, Farrell won't touch the place now. He warns: "I think if there is a competition that anybody is interested in out there, they're better off staying away."

But Farrell says he still likes the country and admires the Chinese. "I think they thought I was an English gentleman," he chuckles.