Fergie’s two O levels… found on a results slip in a dusty old cupboard at her boarding school

She is at the top of the bestseller lists with her children’s books and romantic novels.

However, it has emerged that, contrary to previous reports, the Duchess of York only achieved two O-levels when she sat her exams at a prestigious private school in Berkshire. Her University of London results, for June 1976, were discovered in a dusty filing cabinet during renovation.

They appear to have been accidentally left behind at Hurst Lodge School in Ascot, where the Duchess was a weekly boarder in the early 1970s and which moved to another location five years ago.

Sarah, 64, who later wrote the hugely popular children’s book series Budgie The Little Helicopter and topped the Sunday Times Bestsellers List with two recent novels, is said to have completed six O-levels.

She was a weekly boarder at the school, where fees were about £3,000 a year (which now equates to about £21,000 a year). But the newly discovered document reveals that while the future Duchess achieved an A in spoken English – the equivalent of today’s English oral GCSE – and a C in art, she only achieved a D in English language, English literature and biology , which was subsequently deemed a failure. She also failed French and geography.

Sarah Ferguson (right) with classmates from Hurst Lodge School in Ascot. From left to right: Debbie, Davida Hadden, Sharon O’Toole

The results, along with a letter of thanks to the school for their well wishes after her wedding to Prince Andrew in 1986, were found during a recent renovation of the building by developers.

Last night a source close to the Duchess, who is in talks with streaming giants about their TV adaptations of her Mills & Boon novels, told The Mail on Sunday: ‘Academic qualifications are not the be-all and end-all and the Duchess believes strongly in the importance of emotional intelligence and kindness. The Duchess has always been very open about her lack of formal education and has never claimed otherwise.

‘She is indeed proud that she started out scrubbing toilets for a living and ended up as a Sunday Times bestselling author at the age of 60.’

It is perhaps unsurprising that Fergie, who lives with her former husband in Royal Lodge, Windsor, failed her exams as her teenage years were a time of turmoil. Her mother Susan left her husband, Major Ronald Ferguson, in 1972, leaving him to raise their two daughters, Jane, then 15, and 13-year-old Sarah.

In her 1996 book My Story, the Duchess admitted she was struggling at school: ‘In the summer of 1974 my thoughts were everywhere but my studies. Mathematics eluded me, and I worked on my English, but couldn’t concentrate.’

The results appear to have been accidentally left behind at Hurst Lodge School in Ascot, where the Duchess was a weekly boarder in the early 1970s and which moved to another location five years ago.

In her 2011 book Finding Sarah: A Duchess’s Journey to Find Herself, she also revealed that she had learning disabilities.

‘I had myself assessed by experts who confirmed that I have ADHD and moderate dyscalculia [difficulty in understanding numbers],” she wrote.

However, the Duchess also revealed that she believed you could be ‘successful’ without passing exams.

“I was very successful in school,” she added. “I was made ‘head girl’ – which is the equivalent of class president. I was the winning netball captain. I was also the leader of our class, gregarious and dramatic, with a talent for stirring up mischief.”

The Duchess left Hurst Lodge at the age of 16 and took a course in shorthand, typing and bookkeeping at the Queen’s Secretarial College in London.

Classmate Charlotte Eden, the daughter of former Conservative MP Lord Eden of Winton, remembers: ‘We were both stupid at shorthand and typing. We used to sit at the back of the classroom and giggle.”