It has been said that Princess Margaret and Princess Diana endured a frosty relationship, particularly following the breakdown of the younger royal’s marriage to then-Prince Charles. Margaret and Diana were neighbours at Kensington Palace for years but the two women did not often see eye-to-eye, with Margaret reportedly devastating the Princess of Wales with her hostility. Known as the monarch’s ‘rebel sister,’ Margaret’s ‘antics’ are well-documented: her colourful personality and controversial history have been the subject of headlines, books and TV shows. Now, a royal author has given further insight into the reasoning behind one of Margaret’s seemingly dramatic decisions – and it is not as malicious as it may sound. Gareth Russell, author of the new book ‘Do Let’s Have Another Drink! The Dry Wit and Fizzy Life of Queen Elizabeth the Queen Mother,’ was a guest on this week’s episode of the To Di For Daily podcast. He claimed that Margaret ‘burned all of Diana’s letters to the Queen Mother,’ alongside ‘hundreds, maybe thousands of others,” and added: ‘From a historian’s perspective, it’s horrifying.’But after delving further into the history, Mr Russell discovered that burning letters ‘used to be the equivalent of aristocrats wandering off like elephants to the graveyard. It’s what they did.’ He continued: ‘A lot of them burnt a lot of letters so for instance, Elizabeth II’s grandmother, Alexandra of Denmark, who was our Queen Consort from 1981 to 1910, had a completely unremarkable private life – nothing scandalous. But she burned the letters. READ MORE: Royal system was ‘cruel to spare’ Harry and ‘edged him and Meghan out’ of Firm Margaret reportedly ‘burned all of Diana’s letters’ to the Queen Mother (Image: Getty Images) Diana’s letters were just some of many that were destroyed (Image: Getty Images) Diana’s mother burned many of the Princess’ letters following her untimely death (Image: Getty Images)Diana’s mother, Frances Shand Kydd, came from a noble aristocratic background where there would have been ‘no hesitation’ in burning private letters, according to Mr Russell. But the historian noted the particular significance the Queen Mother’s letters would have held, arguing she ‘was one of the most important Queen Consorts in British history’. Margaret burned a ‘decade’s worth of stuff’ which not only came to the horror of Mr Russell but also Kenneth Rose, a fellow historian and friend of the Princess. The royal biographer tried to stop Margaret from burning all of the important correspondence alongside one of the Queen Mother’s ladies-in-waiting – Lady Prudence Penn. DON’T MISS Meghan Markle admitted she has a ‘food fixation’ on podcast [INSIGHT]Who is your favourite member of the Royal Family? [POLL]Prince Harry ‘obsessed’ with staying relevant over Prince George [REVEALED] Margaret reportedly deemed the letters too private to ever be public (Image: Getty Images)Years later, Mr Rose wrote about the destruction of the letters in his private diary, an entry that has since been published in the Daily Mail: ‘Prue Penn managed to get hold of [the Queen Mother’s steward] William Tallon alone this morning and asked him what exactly had taken place when Princess Margaret descended on Clarence House six or seven years ago to ‘tidy up Mummy’s sitting room’.’She spent a week going through every drawer, wearing white gloves and stopping only for a picnic lunch, throwing away most of her mother’s personal correspondence. She filled no fewer than 30 black bags with the papers, which William thinks were shredded…’Since this happened, the Queen Mother has no longer kept the letters of her friends, but tears them up when read and answered. What a terrible act of destruction.’Similarly, William Shawcross, who wrote the official biography of the Queen Mother, claimed Margaret burned ‘large black bags of paper’. According to some, Margaret was only trying to protect her mother (Image: Getty Images)In his book, he wrote: ‘No doubt Princess Margaret felt that she was protecting her mother and other members of the family. It was understandable, although regrettable from a historical viewpoint.’At the time, the Queen Mother was in Scotland, and Margaret wrote that she planned to go to Clarence House and Royal Lodge, her mother’s home at Windsor Castle.In a letter to her mother, she said: ‘I am going back today to clear up some more of your room. Keeping the letters for you to sort later.’The following day, she wrote: ‘Darling Mummy, I am sitting in your sitting room doing a bit of sorting … I’ve nearly cleared the chaise longue and made an attack on the fire stool.’According to Shawcross, Margaret later told Lady Penn, that among the papers she had destroyed were letters from the Princess of Wales to the Queen Mother because they were so private.