• Queen Elizabeth and Prince Charles advised Prince William not to rush things with Kate Middleton
  • Middleton admitted that she was not happy during her split from Prince William
  • Prince William advised Prince Harry to slow down with his romance with Meghan Markle while the two were still dating

Prince William took his time before he proposed and married Kate Middleton because Queen Elizabeth II and Prince Charles told him not to rush things. Interestingly, he gave the same advice to his younger brother, Prince Harry, when the latter started dating Meghan Markle.

Royal biographer Robert Lacey is releasing a new book, entitled "Battle of Brothers: William, Harry and the Inside Story of a Family in Tumult," on Oct.1 5. In an excerpt published by the Daily Mail, Lacey shared the time when the Duke and Duchess of Cambridge broke up on April 11, 2007, years before they got engaged and married.

"William turned to his father and grandmother for guidance. The Queen had grown very fond of Kate, but she told him he shouldn't rush into a commitment — and his father advised the same. In any case, William was enjoying the life of a hard-drinking Army officer. Not for nothing was his new regiment known as the 'Booze and Royals'," Lacey wrote.

Shortly after hearing his grandmother and father's words, he was seen partying in London. He broke up with Middleton at the time. However, he found dating difficult after his split from Middleton. Several women turned him down because they knew his heart still belonged to someone else.

It didn't take long for Middleton and Prince William's phone calls to resume. After less than 11 weeks since their separation, they were seen kissing and dancing at a party in the prince's barracks in Bovington, Dorset.

During their engagement interview in 2010, the couple opened up about their split. Middleton admitted that she was not happy when they parted ways, but it gave her the opportunity to discover new things about herself.

"I think I at the time wasn't very happy about it, but actually it made me a stronger person," Middleton said. "You find out things about yourself that maybe you hadn't realised. Or I think you can get quite consumed by a relationship when you are younger."

Prince William and Middleton got engaged in 2010 and married a year later. The two share three children together, Prince George, Princess Charlotte and Prince Louis. They celebrated their ninth wedding anniversary in April.

Meanwhile, Lacey claimed that Prince William advised Prince Harry to slow down with his romance with Meghan Markle while the two were still dating. He even asked their uncle, Charles Spencer, to intervene, which only infuriated Prince Harry more.

"The response from Harry was a brusque and offended pushback," Lacey wrote.

Britains Prince William and Kate Middleton Britain's Prince William and Kate Middleton are pictured on a five-day visit to Pakistan. Photo: AFP/Aamir QURESHI