Zhang was based in Hong Kong when she met Pan. It was her second time living in the city. She first came to Hong Kong as a 14-year-old, making zippers in a Tai Kok Tsui factory during the day and going to school at night. She left five years later to attend the University of Sussex in England and then Cambridge, where she majored in economics. After graduating, she returned to Hong Kong and into a more lucrative line of work.

'I started at Barings; I was there for only a few days,' she says. 'When I turned up I realised the whole team had been headhunted by Goldman Sachs, so I joined them.'

But Zhang was eager to return to the mainland. She'd left in 1980, when the country was in the throes of transformation into a capitalist economy. 'All the intellectuals were engaged in the debate about what to do, the direction of the country. I was outside all that time, but I was always seeking opportunities to go back,' she says.

Now the debate has shifted from faith in capitalism to faith itself, says Pan, who was in Hong Kong last week to address a conference on Taoism. 'No one is really starving any more,' he says. 'What's different in recent years is that having enough to eat, [we realise] only accumulating material wealth is not enough for a country's future. A more important question is how do we grow spiritually? What is the importance of spirituality and what brings us to it?'

'Going forward, is Deng Xiaoping's [motto of] 'let some people get rich first' enough?,' Zhang says. 'Is it enough to bring us a glorious culture and civilisation? If not, what is missing? And what more do we need to do?

The couple publish Soho Xiao Bao, a culture and lifestyle newsletter. It began as a means of keeping clients abreast of progress at construction sites, but the couple soon realised no one was interested in project reports and turned their minds to what they thought people really wanted to read.

'We started hiring people to write - real writers. Gradually, it has become such a writers' corner that all the top writers want to contribute,' says Zhang. Mainland law limits internal publications to 20,000 copies, but a Soho China representative claims demand for the free bimonthly is 10 times that.

Pan has also started writing. He began a blog on his website, with subjects ranging from books he'd read to creativity, corporate responsibility, world peace and US politics. It proved so popular he was invited to contribute his blog to the national web portal Sina.com.

Sina says Pan's blog is among the top 10 on the mainland, with more than 35 million hits to date.

Pan's already high profile seemed set to rise further three years ago when Hollywood power broker Creative Artists Agency recruited him to host a Chinese version of US reality TV show The Apprentice. Pan first agreed to serve as the lynchpin employer, giving challenging tasks to wannabe junior executives and telling one of them to hit the road at the end of each episode, but backed out at his wife's behest.

'I was really against it,' says Zhang, who felt her husband should not take on the ruthless, hard-nosed role that Donald Trump had on the show. When Pan broke the news about his venture, she told him, 'You're a model for overcoming poverty. You have an image to uphold. You can't do this!''

'I knew nothing about Donald Trump,' Pan confesses. 'I knew nothing about The Apprentice. But after talking to Zhang Xin, I realised I wasn't the right person to do it.'

He has good reason to trust his wife's sensibilities. Though she bears the title of chief executive officer at Soho China, Zhang might just as well be known as its creative director. She has steered the company from strength to strength, signing up top architects, Chinese and western, for prize-winning projects.

'It doesn't matter if an architect is famous or not, male or female, Chinese or foreign,' she says. 'What matters is whether we think they're good, if we like their work.'

Zhang clearly has a winning sense of aesthetics. At the 2002 Venice Biennale she was presented with a special patron's award - the first of its kind at the event - for the Commune by the Great Wall project, which features a cluster of modern luxury homes each designed by a leading architect.

'Since the Commune by the Great Wall, a lot of architects and developers have realised the importance of quality architecture,' Zhang says. 'A successful development doesn't necessarily require good architecture, but more developers and architects are paying attention to it.'

Zhang also encourages architects to develop more distinct identities. 'Architecture firms in China used to have numbers,' she recalls. 'The No 1 Architecture Institute, the No 2 Architecture Institute - nobody had a name. When I first approached [architect] Cui Kai he was at the No 2 or No 3 Institute of something or other. I said, 'We can't have this number, we need your name'.'

Most of Soho China's residential and commercial developments - covering 2.45 million square metres in total - are in Beijing's central business district and are known for their bold, modern, and often minimalist style.

Nevertheless, Zhang mourns the large-scale destruction of the city's old hutongs. Just a quarter of the capital's traditional streets remain, mostly in the area around the Forbidden City, she says.

'People say it is inevitable to destroy so much [of the old city] because Beijing is undergoing such a drastic stage of development. But I think there are good examples in other parts of the world where the new parts of the city co-exist with the old. Beijing has clearly been less careful in this regard,' she says. 'But in recent few years, as Chinese have travelled more and become more integrated with the rest of the world, appreciation for our own history and culture has increased.

'You see more people wanting to keep memories of the past, but there is very little left.'

Having helped to reshape large tracts of space in Beijing, Zhang and Pan are now on a self-appointed crusade to remake its spirit. They've been reading up on the world's religions to tackle what they view as some of the most important questions in China today.

'We have done a lot of research on Taoism, Buddhism. We've read a lot, met a lot of people and so on, but frequently we've been disappointed,' Zhang says. Many practitioners are locked in 'superstitious, dogmatic ritual', she says. 'You don't really see the spiritual energy there.'

Lest anyone think they've turned into ascetic apostles, Pan says the pursuit of profit remains a priority. 'But we're are also focusing much more on what we need to create an environment where individuals are allowed to grow spiritually,' he says.

'It's very much the debate that China is having today,' Zhang says. 'Are we entitled to have a new faith? We were all communists before, but under the constitution Chinese are free to believe in anything they want, right?'