Historian Robert Lacey said that Prince Harry and Meghan Markle stepping back as senior royals has actually worked in the favour of Prince Wiliam and Kate Middleton because it boosted their public image.

The 77-year-old author, who wrote of a number of best-selling biographies including that of Queen Elizabeth II, shared his observations in the new ITV documentary "The Day Will and Kate Got Married," which aired on April 7.

Lacey said that after Megxit, the Duke and Duchess of Cambridge no longer have to worry about any competition with the Duke and Duchess of Sussex. Prince Harry and Meghan Markle actually made life simpler for them when they left the U.K.

"In a sense, life for William and Catherine became more simple when Harry and Meghan walked out of the picture and there was no competition anymore or confusion about who were the star couple," he explained.

"The challenge of that is that they are now the star couple – and the only couple," he added.

Lacey, who provided input for the Netflix series "The Crown," also spoke up about the rift between brothers Prince Harry and Prince William. He said their conflict "will be resolved one way or another." He echoed what the Duke of Sussex told Oprah Winfrey, that he needs time to patch things up with his brother after he described his relationship with him as "space."

Meanwhile, Katie Nicholl, who wrote "When Harry Met Meghan," said Prince Harry meeting Meghan Markle was a turning point in his life. It gave him the reason to branch out or leave being a "third wheel" to Prince Wiliam and Kate Middleton.

"William and Harry, for many years, had an incredibly close relationship, this unbreakable bond between two brothers who lost their mother. But when Harry met The One, he couldn't live in the shadow of the Cambridges for any longer," Nicholl said in the documentary.

"The Day Will and Kate Got Married" looks back on the wedding of Prince William and Kate Middleton, who will be celebrating their 10-year wedding anniversary on April 29. Prince Harry was the best man during the ceremony.

royal christmas
Princess Beatrice, Princess Eugenie, Princess Anne, Princess Royal, Prince Andrew, Duke of York, Prince William, Duke of Cambridge, Catherine, Duchess of Cambridge, Meghan Markle and Prince Harry attend Christmas Day Church service at Church of St Mary Magdalene on 25 December 2017 in King's Lynn, England. Chris Jackson/Getty Images