The revelation will raise further questions about whether the couple sought permission from the Queen to use her pet name or rather “told” her after the baby had been born.
A spokesperson for the Sussexes said they purchased a “significant” number of domain names for a range of potential names they were considering.
It suggests that had the Queen objected to the use of Lilibet, the couple did have other options.
The domain name lilibetdiana.com was purchased in the US on June 4, the day the baby was born and two days before the public announcement, fuelling speculation the couple had bought it either to prevent others cashing in or with the intention of setting up a foundation in her name.
Several days earlier, on May 31, the domain name lilidiana.com was registered, suggesting the couple had already settled on the baby’s name.
The spokesperson for the couple said: “[As] is often customary with public figures, a significant number of domains of any potential names that were considered were purchased by their team to protect against the exploitation of the name once it was later chosen and publicly shared.”
The name Lilibet was first used by the young Princess Elizabeth when she was unable to pronounce her name properly. It has only been used by her parents, her husband Prince Philip and her closest friends and relatives.
The question of whether Harry and Meghan sought permission from the Queen to use the name for their second child caused a legal row after the BBC reported that they had “never asked”.
Lawyers instructed by the Sussexes said it was “false and defamatory” for the corporation to suggest the couple did not ask the Queen. Harry and Meghan have always insisted that they would not have used the name if the Queen had not been “supportive” of their choice.
But rather than confirming their version of events, Buckingham Palace refused to deny suggestions that the Queen had not been asked.
The couple’s spokeswoman said: “The duke spoke with his family in advance of the announcement; in fact, his grandmother was the first family member he called,” she said.
“During that conversation, he shared their hope of naming their daughter Lilibet in her honour.
“Had she not been supportive, they would not have used the name.”