Tony Earnshaw: What's next for bright young Harry Potter actress Emma Watson?

Then he sat her down for what Emma, aka Harry Potter's Hermione Granger, has described as "the money conversation". Only then did she realise and accept, albeit with much gulping and amazement, that she was worth millions and millions of pounds.

Back in February Vanity Fair magazine listed her (and co-stars Daniel Radcliffe and Rupert Grint) among its Hollywood top earners for 2009. In fact, Miss Watson, now 20, came in at number 14 – highest among the females beating the likes of Cameron Diaz and Angelina Jolie. She's earned every penny. Watson was nine when she landed the role of Hermione in what would become a phenomenal rollercoaster of a movie franchise.

Her childhood has been subsumed beneath an ever-increasing melange of all things Potterian. Her world has become inextricably interlinked with that of JK Rowling's bespectacled wizard. She and Hermione have become one in the eyes of millions. Like Radcliffe and Grint, Watson's tender years have been gobbled up by big business. That's not to say that neither she nor her co-stars have emerged as level-headed young people, because they have. They're a credit to the industry.

But she's soon to emerge from the protective cocoon of the Harry Potter production line and, as the real world beckons, she will need a carapace of her own invention. Her estimated 20m fortune will assist with that.

Observing Emma Watson over the years, and seeing her pursuit of academia at Brown University in Rhode Island (where she eschewed fancy accommodation for standard student digs), reminds me of Jodie Foster, who largely dropped out of acting in the early 1980s to study at Yale.

Foster sought a life outside showbiz and had it not been for the attention around John Hinckley's botched assassination attempt on Ronald Reagan in 1981 – a moment that threw her private life into stark relief since Hinckley had been "inspired" to shoot the president by watching Foster's 1975 appearance in Taxi Driver – she may well have abandoned movies altogether.

Foster returned to more mature roles in triumph, winning Best Actress Oscars in 1989 and 1992 for The Accused and The Silence of the Lambs. Emma Watson has not had anything like the same career as Foster but she possesses similar drive, self-discipline and fierce intelligence.

Who knows whether she'll continue as an actress? But with 20m in the bank, she can take her time making up her mind.