Princess Margaret (left) and Princess Diana.Photo: Princess Diana Archive/GettyWhenPrincess Dianajoined the royal family,Queen Elizabeth’s sister, Princess Margaret, welcomed her as a breath of fresh air amid others' doubts.At first, Margaret saw a kindred spirit in Diana, who struggled to find her own place within the royal family.“Neither of them were hunting, shooting or fishing types,” Andrew Morton tells PEOPLE in this week’s issue. “Margaret put her arm around Diana. She could see they were two metropolitan princesses.““Princess Margaret came to her rescue, suggesting to the Queen that Diana was having difficulties adjusting to her role and that she should cut her some slack,” Morton writes in his new bookElizabeth & Margaret: The Intimate World of the Windsor Sisters. “The Queen, who avoids family confrontation if at all possible, took her sister’s advice.“Morton tells PEOPLE of Margaret, “She did say, ‘Just give Diana a chance.“Princess Diana (left) and Princess Margaret.Kypros/GettyCan’t get enough ofPEOPLE’s Royals coverage?Sign up for our free Royals newsletterto get the latest updates onKate Middleton,Meghan Markleand more!Princess Diana (left) and Princess Margaret.Tim Graham Photo Library via GettyBut in 1995, after Diana aired her grievances to the BBC’s Martin Bashir in her explosivePanoramainterview, “the guillotine really came down,” says Morton.Breaking away from the royal family’s practice of keeping a “stiff upper lip,” Diana spoke candidly with Bashir about the breakdown of her marriage toPrince Charles, the pressures of royal life, her mental health struggles and the lack of support she felt within the royal family.From left: Princess Margaret, Princess Diana and Prince Charles.Anwar Hussein/WireImageGet the premiere issue ofPEOPLERoyalsfor glamorous new photos and inside stories royals fans haven’t seen or read elsewhere!Margaret, who died in 2002 at age 71, “had always defended the Queen and was always loyal to her. She felt Diana let her sister down. She was the Praetorian guard of her sister.”

Princess Margaret (left) and Princess Diana.Photo: Princess Diana Archive/Getty

Princess Diana and Margaret

WhenPrincess Dianajoined the royal family,Queen Elizabeth’s sister, Princess Margaret, welcomed her as a breath of fresh air amid others’ doubts.At first, Margaret saw a kindred spirit in Diana, who struggled to find her own place within the royal family.“Neither of them were hunting, shooting or fishing types,” Andrew Morton tells PEOPLE in this week’s issue. “Margaret put her arm around Diana. She could see they were two metropolitan princesses.““Princess Margaret came to her rescue, suggesting to the Queen that Diana was having difficulties adjusting to her role and that she should cut her some slack,” Morton writes in his new bookElizabeth & Margaret: The Intimate World of the Windsor Sisters. “The Queen, who avoids family confrontation if at all possible, took her sister’s advice.“Morton tells PEOPLE of Margaret, “She did say, ‘Just give Diana a chance.“Princess Diana (left) and Princess Margaret.Kypros/GettyCan’t get enough ofPEOPLE’s Royals coverage?Sign up for our free Royals newsletterto get the latest updates onKate Middleton,Meghan Markleand more!Princess Diana (left) and Princess Margaret.Tim Graham Photo Library via GettyBut in 1995, after Diana aired her grievances to the BBC’s Martin Bashir in her explosivePanoramainterview, “the guillotine really came down,” says Morton.Breaking away from the royal family’s practice of keeping a “stiff upper lip,” Diana spoke candidly with Bashir about the breakdown of her marriage toPrince Charles, the pressures of royal life, her mental health struggles and the lack of support she felt within the royal family.From left: Princess Margaret, Princess Diana and Prince Charles.Anwar Hussein/WireImageGet the premiere issue ofPEOPLERoyalsfor glamorous new photos and inside stories royals fans haven’t seen or read elsewhere!Margaret, who died in 2002 at age 71, “had always defended the Queen and was always loyal to her. She felt Diana let her sister down. She was the Praetorian guard of her sister.”

WhenPrincess Dianajoined the royal family,Queen Elizabeth’s sister, Princess Margaret, welcomed her as a breath of fresh air amid others’ doubts.

At first, Margaret saw a kindred spirit in Diana, who struggled to find her own place within the royal family.

“Neither of them were hunting, shooting or fishing types,” Andrew Morton tells PEOPLE in this week’s issue. “Margaret put her arm around Diana. She could see they were two metropolitan princesses.”

“Princess Margaret came to her rescue, suggesting to the Queen that Diana was having difficulties adjusting to her role and that she should cut her some slack,” Morton writes in his new bookElizabeth & Margaret: The Intimate World of the Windsor Sisters. “The Queen, who avoids family confrontation if at all possible, took her sister’s advice.”

Morton tells PEOPLE of Margaret, “She did say, ‘Just give Diana a chance.”

Princess Diana (left) and Princess Margaret.Kypros/Getty

Princess Diana and Margaret

Can’t get enough ofPEOPLE’s Royals coverage?Sign up for our free Royals newsletterto get the latest updates onKate Middleton,Meghan Markleand more!

Princess Diana (left) and Princess Margaret.Tim Graham Photo Library via Getty

Princess Diana and Margaret

But in 1995, after Diana aired her grievances to the BBC’s Martin Bashir in her explosivePanoramainterview, “the guillotine really came down,” says Morton.

Breaking away from the royal family’s practice of keeping a “stiff upper lip,” Diana spoke candidly with Bashir about the breakdown of her marriage toPrince Charles, the pressures of royal life, her mental health struggles and the lack of support she felt within the royal family.

From left: Princess Margaret, Princess Diana and Prince Charles.Anwar Hussein/WireImage

Princess Diana and Margaret

Get the premiere issue ofPEOPLERoyalsfor glamorous new photos and inside stories royals fans haven’t seen or read elsewhere!

Margaret, who died in 2002 at age 71, “had always defended the Queen and was always loyal to her. She felt Diana let her sister down. She was the Praetorian guard of her sister.”

source: people.com