If there were a prize for the people’s architect, then Sir Terry Farrell would win it. His career has ranged from creating the TV-am headquarters in Camden, north London, with its distinctive egg-cup finials, to the grand Beijing South Railway Station. A robust champion of people-friendly urban design, he is currently planning west London’s 72-acre Earl’s Court exhibition site.

Farrell lives with his third wife Mei Xin Wang, a mining consultant from Beijing. The couple met at a wedding in Cambridge and now live in a three-bedroom apartment at the top of a former aeroworks plant in north-west London.

Their home reflects its industrial heritage. Just inside the door, two round metal sinks have been converted into large fish bowls. They flank the imposing municipal metal staircase that used to be in the office and now leads up to Farrell’s loft. “It’s a kind of Busby Berkeley staircase with an industrial edge,” says the 71-year-old, dressed in an orange shirt with muted trousers and jacket.

Farrell’s love of the flamboyant appears in an oversized lamp that stands at the top of the stairs. Next to it a plush purple throne of a chair looks like something straight out of a Hollywood musical. “I proposed to my wife in that chair,” he says. A large model of the Red Baron’s triplane from the first world war is suspended nearby, one of many model aeroplanes that hang in the apartment.

“I like models,” Farrell says. “It kind of reawakens the childlike thing – you can see the whole object and it gives it accessibility.” The overall Biggles-meets-Heal’s effect is original, fun and, given the industrial architecture, welcoming.

“It is definitely more comfortable since Mei Xin moved in five years ago,” he says. “It’s become softer. Somebody once said, ‘Terry, this is a soft loft.’ Because lofts can be very hard,” he adds.

Steel pipes run alongside patterned carpets while factory-like aluminium shutters open on to miniature potted palm trees. There are also papier mâché cars and unusual lights. “I do a lot of town planning and the thing I like is the sheer diversity of the buildings in the street,” says Farrell. “I am a maximalist.” This means that he eschews the monastic minimalism of so many of his peers.

Farrell’s humour and eccentricity are on view throughout the apartment: on a replica of the couple’s wedding cake, traditional figurines are replaced by a bride carrying a dishevelled groom. Can any meaning be read into this? “I don’t know. I didn’t choose it,” says Farrell, slightly embarrassed.

The son of a postmaster, he grew up in a humble home in Newcastle and spent most of his childhood building models and drawing. “It worried my mother as to how I would earn a living. There was no such thing as an artist in the family,” he says. When he was 14, his mother suggested he study to become an architect. An art teacher who recognised Farrell’s artistic talents helped him get in to university. “It never occurred to me to go,” he says. He ended up earning a first-class degree in architecture and found, when he started work, that he was already earning half as much as his father.

“At that point the penny dropped for my parents that I could earn a decent salary and they felt more secure. However, they worried again when I started up my own practice,” he smiles.

Farrell’s acquisition of the old aeroplane factory, initially to house his business, was a shrewd process of borrowing from “Peter to pay Paul”. “I didn’t have a penny and I was short of work,” he says. In 1985 he purchased 63,000 sq ft of building space for £630,000 while also trying to sell off several apartment-sized portions he did not actually need. “It took me six months to get it all together and I made £40,000,” he says.

Farrell sold some of the apartment spaces under the condition that he would be appointed as their architect. “The conversions all had to be done as one, with new staircases and fire escape routes. I had to process about a dozen different people’s workplaces,” he says.

Eventually, in 2000, when his second marriage of 30 years was coming to an end, Farrell moved his growing business to the ground floor he now owns and converted the original office into his home. “I have always capitalised on the value I can add to where I am living. This has been a great investment for me,” he says.

In order to turn the loft into a more liveable space, Farrell started by putting in an impressive warehouse-like glass and aluminium roof, flooding the space with light. An atrium was then added around the stairwell. “It’s like a true atrium – in a classical house – so the garden is in the centre and you gather around it,” he says. A collection of succulents and cacti are displayed in Mei Xin’s ceramic plant pots, all from Beijing, on one side of the atrium.

“Cacti are incredibly architectural. They have an inner structure of geometry,” says Farrell, whose love of biology and nature has informed much of his work over the years. Landscape, parks and walkways are at the heart of his master plan for the Thames Gateway regeneration; if his vision survives cuts and new leadership, Farrell sees the area becoming as attractive as the Thames Valley.

Farrell can spend hours working on plans and drawings sitting at the kitchen table next to his plants, his favourite corner of the house. However, as the day progresses, he will “safari a bit” and move to the top of the stairs in pursuit of some sunshine or he’ll “retreat to the sofa at the foot of the bed when I find it gets too hot”.

The master bedroom, like the bathrooms, spare bedroom, terrace entrance and Mei Xin’s busy study, radiate off the large open-plan kitchen and dining area. “It’s rather like a Scottish castle with big space in the middle and little spaces around,” he smiles. And Farrell is its king.

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