Rare photographs of Princess Diana during her school days have been unearthed in a new auction collection.

The pictures, shared by former classmate at West Heath Girls’ School in Kent, Katherine Hanbury, show the royal sitting outside in the sun with a number of friends, including actress Tilda Swinton and film director Joanna Hogg.

Others show the former Princess of Wales outside the art room, one of her in a block known as the ‘cowsheds’, and standing outside, close to the playing fields. 

The images are among a collection of items to be auctioned by Ms Hanbury. 

They will go under the hammer at Gorringe’s Fine Art and Interiors sale in Lewes, East Sussex, in July and are estimated to fetch up to £6,000.

Albert Radford, books and manuscripts specialist at the auction house, said: ‘This intimate archive offers a rare glimpse of Diana, Princess of Wales, before duty and fame had the final say.

‘She appears here as a young woman suspended between love and history - hopeful, unguarded, and not yet entirely claimed by the institution that would come to define her.

‘In these small, fragile traces, innocence lingers - along with a quiet stubborn belief in something as simple and elusive as love.'

The collection also includes a previously unpublished letter, dated September 27, 1981, to Ms Hanbury.

As a newlywed, Diana told her school friend she loved being in Scotland and ‘playing with grown ups’ at Balmoral - and also claimed to ‘hate’ London.

She famously had a ‘complex’ relationship with being north of the border. Although the princess adored exploring the the private estate in Royal Deeside, she found the strict protocol, intense security and rigid atmosphere of the castle exhausting and stressful.

But writing from Balmoral shortly after her wedding to the then-Prince Charles, Diana painted a different picture.

She said she had enjoyed ‘endless sun’ and ‘calm seas’ during a cruise on the Royal Yacht Britannia.

Diana married Charles when she was 20, having left school at 16 and dropped out of a finishing school in Switzerland before starting work in a nursery.

In her note, written on royal-crested paper and sent to her friend, she said: ‘We had a blissful honeymoon with endless sun and luckily calm seas. We are now up in Scotland until the end of October, which is a big treat for us - I adore being outside all day & hate London!’

She also added: ‘Its [sic] wonderful being married - I think its [sic] safe to say that after two months!’

The letter suggests she was adapting to her new life and role within the Royal family as she wrote: ‘Its [sic] a case of playing with grown ups!’

Diana and Charles had boarded the Royal Yacht Britannia after their wedding on July 29, 1981 for a 12-day cruise of the Mediterranean before heading to Balmoral for several months.

Diana married Charles at St Paul’s Cathedral with an estimated 750million people watching across the world.

They separated in 1992 and, following the Queen’s intervention, their 15-year long union officially ended in August 1996.

The princess died in a crash in Paris the following August. West Heath Girls’ School closed in 1997.