The 63-year-old underwent surgery in June after she was diagnosed with an early form of breast cancer.

It was discovered during a routine mammogram, which she has urged others to go for.

The Duke of York's ex-wife had single mastectomy surgery and explained on the latest episode of her Tea Talks podcast that naming her new breast had helped her move forward.

She said: "I am just coming to terms with my new best friend Derek, on my left, he's called Derek.

"He's very important because he saved my life."

Asked why she picked the name by her co-host Sarah Thomson, the duchess replied: "I don't know.

"It just made me laugh that I have now a friend who is with me all the time who is protecting me with his shield of armour."

Joking about her "perky friend on my left", she added: "Poor Eric on the right is feeling rather sad because he is not as perky as Derek on the left but I will get Eric balanced, don't worry."

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The duchess praised the "amazing work" of the surgeons and doctors who helped her.

She said is "getting much better", but since she does not feel able to travel for about a month as she recovers, she added she can perhaps plan for next year's holidays.

The duchess has two daughters with her former husband, Prince Andrew - Princess Beatrice, 34, and Princess Eugenie, 33.

In an earlier podcast, she spoke of being "blown away" by the love she had received from around the world after the eight-hour operation.

She said it had been "moving" to receive a note saying: "You are the strongest, bravest person I know and it's because of you that I'm still here."

The support she has received had given her strength to "go forward", she said.