Sarah, Duchess of York passed only two O-levels while at a top boarding school

It appears to have been accidentally left behind at Hurst Lodge School in Ascot, where the duchess was a weekly boarder in the early 1970s, and shows she only passed spoken English, with an A, and art, with a C.

Fees at the posh school were about £3,000 a year - equivalent to £21,000 a year today.

The results also show Sarah got Ds in English language, English literature and biology, which then counted as a fail.

She also failed French and geography.

Sarah has gone on to write the 'Budgie the Little Helicopter' series of children's books and topped the Sunday Times bestseller list with two romance novels titled 'Her Heart for a Compass' and 'A Most Intriguing Lady'.

A source close to the Duchess, who is in talks with streaming giants over adaptations of her novels, told The Mail on Sunday: "Academic qualifications are not the be-all. The Duchess has always been very open about her lack of a formal education.

"Indeed, she is proud of the fact she started out scrubbing toilets for a living and has ended up as a Sunday Times bestselling author."

Sarah left school at 16 and took a course in shorthand, typing and book-keeping at Queen's Secretarial College in London, before she married Prince Andrew, 63, in 1986 - whom she divorced 10 years later.

Sarah's results are said to have been discovered during a renovation of Hurst Lodge School in Ascot, Berkshire.