One of Britain’s most famous businesswomen, Amanda Staveley, returned to her old school with an inspiring message.

Miss Staveley, the financier and former girlfriend of the Duke of York, who arranged the rescue finance for Barclays Bank in 2008 and also organised the purchase of Manchester City FC by Sheikh Mansour, was guest speaker at the annual speech day at Queen Margaret’s School, Escrick.

“Attempt the impossible,” the 38-year-old Ripon-born international deal maker told the pupils, saying there was no limit to what they could achieve.

Miss Staveley attended Queen Margaret’s from 1984 to 1989, taking her A-levels a year early and going to Cambridge University at the age of 17.

She came to prominence in 2008 when, running her own financial consultancy, PCP Capital Partners, she helped raise more than £7 billion of rescue investment from the rulers of Abu Dhabi and Qatar, to bail out Barclays.

In the process, she pocketed a reported £40 million in commission and is now reckoned by the Sunday Times Rich List to be worth at least £100 million.

Describing the Barclays deal to the school’s 300 pupils, plus parents and governors, Miss Staveley said: “I didn’t do it because I was part of a big bank. I did it myself because, to be honest, it looked impossible.

“But I have learned that you shouldn't be put off because people tell you something’s not possible.”

“Everything you do is going to be tough. Being a woman is tough. And there are far more pressures today, life moves at a greater pace, than it did when I was at school here. But don’t let that stop you. Go out and live your dreams.”

The daughter of Robert Staveley, founder of the Lightwater Valley theme park, Miss Staveley was a gifted teenage athlete until a tendon injury ended her sporting ambitions. She recalled being “frequently in trouble” at school, but found Queen Margaret’s “very, very entrepreneurial – very driven”, which had inspired her.

Having failed to complete her Cambridge degree due to stress caused by a family bereavement, she bought a restaurant close to the horse-racing hub of Newmarket, where she met some of the world’s richest racehorse owners – many of them associated with the Gulf rulers whom she later enlisted to save Barclays.

She also arranged the purchase of Manchester City Football Club by Sheikh Mansour of Abu Dhabi, earning a reported £10 million in commission.