Prince Charles' unusual nickname for daughter-in-law Meghan

The Duchess of Sussex has been given a very unusual nickname by her new father-in-law, it is claimed.

Meghan, 36, was initially christened "Tungsten" by Prince Charles because she is tough and unbending, just like the very strong metal, according to palace sources.

It might not appear the most flattering of comparisons, but it is intended as a compliment by Charles, 69, and the affectionate name has stuck.

Prince Charles, Prince of Wales accompanied Meghan Markle partway down the aisle before she married Harry at St George's Chapel in Windsor. Photo / Getty

The source told the Mail on Sunday: "Prince Charles admires Meghan for her strength and the backbone she gives Harry, who needs a tungsten-type figure in his life as he can be a bit of a softy. It's become a term of endearment."

The close bond between Meghan and Charles became apparent when she asked him to walk her down the aisle after her father, Thomas Markle, pulled out of attending the ceremony because of heart surgery.

Speaking on Good Morning Britain, Markle said he couldn't "think of a better replacement than someone like Prince Charles".

There is obvious affection between Prince Charles and his new daughter-in-law. They were spotted having a laugh on Buckingham Palace's balcony following the Trooping of the Colours. Photo / Getty

He said: "He looked very handsome and my daughter looked beautiful with him. I was jealous. I wish I'd been there I wish it had been me but thank God he was there and thank him for that. It might have been a treat for him as he never had a daughter."

It is understood Prince Charles was "terribly touched" to have been asked. Harry whispered "Thanks, Pa", and smiled as Charles left Meghan at his side.

Meghan later thanked Charles in an after-dinner speech during the private wedding party at Frogmore House for the warm welcome.

Thick as thieves: Meghan, Duchess of Sussex accompanied Queen Elizabeth II to Widness last week. Photo / Getty

One source described how Meghan expressed her gratitude at how welcoming the prince had been to both herself and her mother, Doria Ragland.

Meghan appears to be fitting in well with her tightly knit in-laws. Last week she and the Queen, 92, were spotted "laughing like schoolgirls" as they attended their first official joint engagement together in Cheshire.

Body language experts noted how the pair appeared entirely relaxed and comfortable in each other's company.