You’d have to be as stupid as Neville Longbottom not to know Joanne Kathleen Rowling is rolling in money. Harry Potter’s creator is the only billionaire author in the 2008 Forbes world rich list and the only British woman featured, coming in 1,062nd with $1 billion (£504million).

Her story is well documented. As a single mother, suffering from depression and living in a cramped flat with her baby, Jessica, Ms Rowling was able to afford the rent only after a friend paid the £600 deposit.

It was at this time that she began to write the first Harry Potter book in an Edinburgh café, nursing cold coffees. The first in the series, Harry Potter and the Philosopher’s Stone, was launched in 1997 and was an overnight sensation. It won the British Book Awards Children’s Book of the Year and was shortlisted for the Guardian Fiction Award.

The seventh and last instalment was released last July and was the fastest-selling book ever. More than 11 million copies were sold in the first 24 hours. The film version of the fifth book was also rolled out in the same month. Ms Rowling has not only earned millions from her novels about the boy wizard, she also makes a tidy sum from royalties and merchandising from the film adaptations of the books.

And it’s not just JK Rowling who is reaping the rewards. Last year, Advertising Age calculated that the Harry Potter brand is worth in excess of $15 billion. Being stinking rich, however, does not always sit easy with the 42-year-old author. In a 2003 interview with the Newsnight presenter Jeremy Paxman, she said the rewards had been “completely disproportionate”.

Ms Rowling’s story, however, is not a rags-to-riches one. Her childhood was comfortable. She was born in Gloucestershire to Anne and Peter Rowling. Her father is a retired Rolls-Royce engineer. She attended Tutshill primary school and Wyedean comprehensive school, where she was head girl. She went on to obtain a degree in French at Exeter University.

It was as a young adult, after her break-up with her first husband, a Portuguese television journalist, not long after Jessica was born, that Ms Rowling experienced poverty. This may partly explain her philanthropy today.

Ms Rowling has quietly given away great chunks of her money. She gave £22 million to Comic Relief and among many other things has set up a charity, the Children’s High Level Group, to promote children’s rights, particularly those of disabled children in care homes in Eastern Europe.

Ms Rowling has a small property portfolio. Her main residence is reported to be a 13-bedroom house in Edinburgh worth about £2 million. She also has a six-bedroom country home in Perthshire, on the banks of the Tay, and her £4.5 million Kensington pad.