Even though the Duke and Duchess of Cambridge named their first child George, the royal couple did go through the dilemma of choosing the perfect name for their beloved. A royal expert claims that Kate Middleton had a "different name" for her now six-year-old son.

Citing royal expert Katie Nicholl from Vanity Fair, OK! is reporting that the royal couple that celebrated nine-years of marriage last week had another name in mind for Prince George of Cambridge. Nicholl revealed even though the royal parents chose not to find out the sex of their firstborn, Kate had another favourite name for their son; and it wasn't George.

"Although Kate apparently suspected it was a boy and had set her heart on the name Alexander, they had not yet decided what to call their firstborn," Nicholl told the magazine.

It is said that the duchess had her "heart set" on the name "Alexander." Even though it did not become the little prince's first name, Kate's favourite made it to his middle name.

Prince George was born two years after their marriage on July 22, 2013 and was christened George Alexander Louis on October 23, 2013, at The Chapel Royal, St James's Palace.

"Although Kate apparently suspected it was a boy and had set her heart on the name Alexander, they had not yet decided what to call their firstborn," Nicholl said.

It is said that the royal courtiers also insisted that the couple did not find out the sex of their baby and leave it a surprise. However, Kate reportedly referred to her unborn baby as "our little grape" while she was still expecting.

A friend of the couple reportedly told that even Prince William did not want to find out the gender of their baby. "

"There are so few surprises in life' — this was one he wanted to keep," the royal dad apparently told the friend a few weeks before the baby's birth. However, the duchess' motherly instinct told her it was a boy "because the baby kicked so much."

Prince George
The Duke and Duchess of Cambridge have released an official portrait of Prince George to mark his 4th birthday AFP/Getty

Prince George, who is third in the line to the British throne, was named after his great grandmother Queen Elizabeth's father King George VI, who reigned from 1937 to 1952.