How Princess Diana's sister's 'stupid mistake' cost relationship with Prince Charles

Before Princess Diana came into the picture of Prince Charles’ love life, her sister Lady Sarah Spencer was someone who caught his eye.

The two had dated in 1977, attending royal parties and meeting each others’ family however, when pressure mounted on Charles to find a bride, the couple’s romance fizzled out in 1978.

It is alleged that Lady Sarah had decided to call it quits in a manner that Prince Charles called "extremely stupid".

Diana’s sister had essentially gotten candid with a few journalists and shared how she was never in love with him even though the pair were even spotted on a holiday together.

"There is no chance of my [sic] marrying Prince Charles. He is a fabulous person but I am not in love with him, and I wouldn't marry anyone I didn't love, whether he were the dustman or the King of England. If he asked me I would turn him down," she said.

"Prince Charles is a romantic who falls in love easily. But I can assure you that if there were to be any engagement between Prince Charles and me it would have happened by now. I am a whirlwind sort of lady, not a person who goes in for a long, slow courtship.

"Our relationship is totally platonic."

After this, Prince Charles was warned of what was to come on publications the next day to which he told Sarah: "You've just done something extremely stupid".

Eventually in 1980 Charles and Diana crossed paths and the younger Spencer was destined to become his wife.