Prince William and Princess Kate had an adorable nickname for Prince George before he was born, according to a royal author.

As the future heir to the throne, George has many titles but journalist and royal author Robert Jobson revealed in his 2013 book ‘The New Royal Family: Prince George, William and Kate, The Next Generation’ that he had a different nickname before he was born.

While preparing to give birth to George in July 2013, the Princess of Wales had just completed her final public appearance by wowing crowds at Trooping the Colour before heading on 'maternity leave'.

William was about to take his paternity leave from the RAF as they prepared to welcome George, who they had nicknamed their 'little grape' during Kate's pregnancy.

Mr Jobson wrote: "The next time we would see her [Princess Kate] - officially at least - would be on the hospital steps with her new baby in her arms and proud husband at her side. There is no doubt the birth of her baby would be her biggest test to date, and, indeed, it would be a crowning moment.

"Prince Charles was considered progressive to want to be at his wife's side. Like his father, William had followed modern convention by taking two weeks' paternity leave from the RAF to bond with the baby they have nicknamed 'our little grape'.

"As the birth day approached, Kate threw herself into preparing her royal nest. She spent time getting the temporary nursery at Nottingham Cottage, in the grounds of Kensington Palace, ready."

Mr Jobson described Kate and William as "royal trendsetters" throughout the pregnancy as they introduced "far greater informality" to the process.

However, building work at Nottingham Cottage was delayed when asbestos was discovered in apartment 1A, a four-storey house that forms half the Clock Tower Wing.

"For Kate, one of the main attractions of the house, designed by Christopher Wren in the 17th century, is the beautiful walled garden, perfect for pushing the baby around and indulging in some gardening," the journalist and broadcaster wrote in his book.

"With the help of her mother, Kate had been choosing furnishings and fabric for the house in very much the same way that Diana did 30 years before."

Prince William also has his own nicknames, including one given to him by his late mother Diana - 'Wombat'. In a 2007 interview with NBC's Matt Lauer, he explained: "It began when I was two. I've been rightfully told because I can't remember back that far. But when we went to Australia with our parents, and the wombat, you know, that's the local animal. So I just basically got called that. Not because I look like a wombat, or maybe I do?!"

Mr Jobson wrote in the book that Kate meanwhile, was nicknamed "Squeak" as a young girl at St Andrew's School in Berkshire. She explained how the name came about while on a visit to the school years later.

"I was nicknamed Squeak just like my guinea pig," she said. "There was one called Pip and one called Squeak because my sister was called Pippa and I was Squeak."