The “bickering” between Meghan Markle and Kate Middleton reportedly got so out of hand that Queen Elizabeth herself had to step in, a royal author is claiming.

The U.K. Mirror reported that a palace insider told royal author Tom Quinn that the fighting was so out of control that the Queen was driven from Buckingham Palace to Kensington Palace to “try to stop the bickering.”

“At first the couples got on well – William and Harry have always been close – but inevitably there were tensions,” Quinn wrote in his book “Kensington Palace An Intimate Memoir from Queen Mary to Meghan Markle.”

One insider told Quinn that “both William and Harry were always likely to be drawn to confident, strong women because they lost their mother so early. Kate) was very warm towards Meghan when she arrived.”

“But tensions were bound to arise because Meghan inevitably had to accept that that although she is a Duchess she is not married to the next king,” the insider added. “I think she has found that difficult to deal with and although Harry loved their cottage in the grounds of Kensington Palace, Meghan and conscious that it was tiny in comparison to the vast apartment complex where Kate and William live.

“Harry has nothing to prove. Meghan has everything to prove. That’s the problem,” the source explained.  “I know, for example, that tensions reached such a pitch that the Queen herself was driven to Kensington from Buckingham Palace to try to stop the bickering. However others have suggested Meghan and Kate weren’t duelling but “just had nothing in common.”

This comes after royal authors Omid Scobie and Carolyn Durand claimed that Harry and Meghan were jealous of William and Kate in their new book “Finding Freedom.” They also alleged that Harry always felt like a third wheel with William and Kate, meaning he was unhappy with them long before Meghan entered the picture.

“It wasn’t a rivalry between the brothers but more a sense that they would be competing over who would lead on their various issues,” said one source. “Harry felt awkward as a plus one. They’d turn up at premieres and there was this sense that he felt a bit like a spare part. Long before Meghan he wanted to change things. He wanted to control his own narrative. He would say, ‘Why can’t we use social media or record videos and cut out the press?'”