Sarah Ferguson, Duchess of York doesn't think Princess Diana "understood how brilliant she was".

Sarah Ferguson and Princess Diana were good friends

Sarah Ferguson and Princess Diana were good friends

The 63-year-old author was a fourth cousin of the late royal - who died in a car accident in 2017 - but thought it was "just extraordinary" that they were "brought together" by their marriages to Prince Andrew and then-Prince Charles, though they often felt "left in the corner of a room".

Speaking to her co-host Sarah Thomson on their 'Tea Talks' podcast, Sarah said: “She [Diana] never understood how brilliant she was really, you know, and together we both didn’t. And I used to hug her but she wouldn’t understand.”

The duchess explained the pair managed to carve out their own roles through their philanthropic work and she and Diana would talk “incessantly about charity”, and no one could make her laugh more than her friend and sister-in-law.

She said: “We loved each other with all our hearts and she made me laugh more than any other single person I’ve ever met in my life."

Sarah recalled how horrified people were when Diana voiced her intention to work with charities highlighting HIV and AIDS.

She said: “Everyone said, ‘No, you mustn’t go and touch them’. She said ‘why? I know what it’s like to be ostracised. I know what it’s like to be left in the corner of a room’.

“And I know that feeling too, when people don’t wish to talk to you because bad Fergie sells papers.”

And the 'Her Heart for a Compass' writer also alluded to Diana's unhappiness with royal life and admitted she's finally learning lessons herself.

She said: “There was nobody like her in the world because she had that ability to give her entire heart because she didn’t give her entire heart to herself.

“It’s been written about many times, and I have decided at 63 to perhaps start understanding what that means. You have to look after yourself.”

Elsewhere on the podcast, Sarah joked she loves being a grandparent to Princess Beatrice and Edoardo Mapelli Mozzi's 18-month-old daughter Sienna and Princess Eugenie and Jack Brooksbank's sons August, two, and one-month-old Ernest because she can simply "walk out" if they're misbehaving.

She said: “The best thing [about] being a grandmother is when you’re sitting in the room and they’re really being naughty, and they won’t put the nappy on or something, you just get up and walk out."