'Secret feud' existed between Diana and Princess Margaret

Princess of Wales' biographer Andrew Morton has claimed Princess Margaret turned against Diana after she said on a TV show: "There were three of us in this marriage so it's a bit crowded" -- a reference to Prince Charles's relationship with Camilla, the 'Daily Express' reported.

Following the bombshell interview, Princess Margaret sent Diana a "wounding and excoriating" letter regarding her behaviour which was seen as "shocking and unforgivable".
From that day on, relations between the two women -- Princess Diana and Princess Margaret, who died in 2002, soured to such an extent that the Queen's younger sister could not bear to even look at images of Princess of Wales, Morton said.

In fact, she turned against her so-called "neighbour from hell" so emphatically that she would flip over the cover of any magazine in her home that featured Diana on the front.
There was no thaw between the two women even in death with the full extent of the schism demonstrated on the day of Diana's funeral. As her flower-bedecked coffin passed Royal Family, Queen and other members bowed their heads in respect.
But, Margaret was "flint-eyed" and remained upright, "looking as if she would rather be somewhere else", he said.

The revelations came just days after a new official biography of the Queen Mother claimed that Princess Margaret deliberately burnt letters between Diana and her mother as they were "too private".