Chris Bowlby profiles the British-educated Chinese property billionaire Zhang Xin, one of the most powerful women in business. She is in advanced talks to buy 40 per cent of Manhattan's iconic General Motors building.

Zhang Xin stands out as the high-profile CEO of the prominent, upmarket property developer SoHoChina, which she founded with her husband. Unusually for Chinese billionaires, she is also a philanthropist and speaks out about issues ranging from democracy to smog, in the international media and on her micro-blog.

A rags to riches story, she grew up in very modest circumstances, particularly after her Chinese-Burmese translator parents split up, and her mother moved her from Beijing to a tiny room in Hong Kong, where she worked in a factory.

After saving up for the airfare to the UK, she was then educated at Sussex and Cambridge universities, worked for Goldman Sachs, and returned to China where she built up her business with her husband.

What motivates this billionaire mother-of-two to carry on working, particularly as property developers are often reviled in China?