Princess Diana's old boss thought Charles would grow to love his 'warm and beautiful' bride

Princess Diana's former employer says she was convinced that the royal couple would live happily ever after.

Mary Robertson hired the future royal on the spot with absolutely no knowledge of her royal connections after seeing her with her son.

The then Lady Diana Spencer interviewed for a job with Mary Robertson taking care of her little boy Patrick, and was a huge hit with the family.

She soon became close to the Mary and even invited her to the Royal Wedding.

Speaking on British TV for the first time in Channel 5's new documentary Charles and Diana: The Truth Behind their Wedding, she said: "She was very much in love with Prince Charles, or certainly, with the image of Prince Charles.

"Charles was wonderful, he was so charming.

Diana worked for Mary and her family before marrying Prince Charles (Blakeway Productions)

"Diana was head over heels in love with Charles. I just assumed things were going to work out beautifully.

"She was just so appealing and warm and beautiful, it never occurred to me that he wouldn't learn to love her."

Mary hired Diana to look after her son before she became engaged to Charles, offering her a job on the spot after an impressive interview.

She said: "She came over interviewed and she was so good with my son, so natural, down to earth and just beautiful.

"That wonderful thick hair, the big blue eyes, perfect skin. Her voice and her very deferential manner to me.

Mary was good friends with the young Princess (Tim Graham Photo Library via Get)

"I had no idea who she was. I hired her on the spot and she just became part of our life. She and I became pretty good friends.

"I get a little emotional when I think about this sweet little child leaving my home, pushing Patrick in his stroller to face that barrage that never left her alone."

She also spoke about Diana's love of Barbara Cartland books.

Mary was invited to Diana and Charles's wedding (PA Archive/Press Association Images)

Each of the books followed the same theme - a handsome, uniformed man feel in love with a very young and impressionable girl. They married, fell in love and lived happily ever after.

"I think they expected her just to stay in the background and be quiet and follow five steps behind."

Charles and Di: The Truth Behind Their Wedding is on Channel 5 at 8pm on Saturday, 27 July.