As Princess Margaret and Queen Elizabeth grew into their respective roles within the royal family, their differences became even more apparent; Elizabeth was the dedicated monarch who did everything by the book, and Margaret was the rebel who lived life largely on her own terms. As such, there grew both loyalty and tension between the sisters, with famed royal biographer Andrew Morton telling Vogue that Margaret's role as the "backup" only went so far. "There's an awful lot of jealousy because Margaret was the one who commanded attention and she loved the spotlight. It's a complex relationship; it's one of loyalty and support, but also primal jealousy," Morton attested. 

"On one occasion Margaret slams into the queen's drawing room at Windsor Castle whilst the Prime Minister was there; she walks in and, in addressing her, says, 'If you weren't Queen, nobody would talk to you.' That is to say she wasn't that interesting. You see this jealousy and you also see this loyalty that Margaret had towards Elizabeth," Morton said (via Vogue).

Further commenting on the dynamic between the sisters, Anne Glenconner, who served as Margaret's lady-in-waiting, opened up about the element that Margaret was keenly envious of: Elizabeth's education. "She always minded about not being educated as well as the queen," Glenconner told People. "The queen had people from Eton and Cambridge, naturally. But Princess Margaret was never part of that."