Charles Spencer shared a rare photo from his early years alongside his sister, Princess Diana, on her first day of school.

Earl Spencer shared the touching photo dated September 1968 on Instagram with the release of his new memoir A very private school.

The brothers are pictured in matching red blazers with the school logo and gray knee-high socks.

He revealed that he and Diana went to Silfield in King's Lynn, Norfolk, which he fondly considers a “really lovely primary school”.

He wrote: “My first day at school, September 1968: my father took this photograph of me and my sister, Diana, just before taking us to Silfield, a really lovely primary school in King's Lynn, Norfolk.

Earl Spencer shared the touching photo dated September 1968 (Charles Spencer/Instagram)

“The headmistress was Miss Jean Lowe, a warm and caring lady who loved her boys and girls. I stayed there until 1972, when I went to the place I call – in my memories – A very private school.

For secondary education, Spencer, 59, attended Maidwell Hall, an all-boys boarding school, where he says he was the victim of harrowing abuse that led to relentless trauma in later years.

Your memories A very private school released on March 14, he wrote that he was abused by a matron's assistant when he was 11 years old.

He detailed: “There seemed to be an unofficial hierarchy among her prey… she chose one boy each semester to share her bed and used him for sexual intercourse. Her control over the hypnotized boys was total, as we were starved of feminine heat and desperate for attention and affection.”

Spencer later claims that he lost his virginity to an Italian prostitute as a result of the experience. He also said he was physically beaten by the spikes of a cricket boot from the school's Latin master.

He said People: “I always felt like I had dealt with that chapter of my life and had closed it. But talking to classmates and hearing their experiences was very empowering for me. I would be very struck by the horror of what they had shared. And that was the hardest part.”

Despite being extremely close to his sister, he says he never told her about the horrors that happened behind the school gates.

The 59-year-old only opened up to fellow sisters Sarah and Jane 18 months ago, who were “stunned and horrified”.

In a statement to the media, Maidwell Hall said it was “sorry” for the experiences Earl Spencer and some others had at the school.

“It's difficult to read about practices that, unfortunately, were sometimes considered normal and acceptable at that time. In education today, almost every facet of school life has evolved significantly since the 1970s. At the heart of the changes is safeguarding children and promoting their well-being.

“While we have not directly received any complaints from former students, given what has been reported, the school has followed the legal process and forwarded it to the Local Authority Designated Officer (LADO).”