Princess Catherine's idea that Meghan Markle found very difficult

Princess Catherine's idea for her and Prince William to do the Windsor walkabout was 'difficult' for Meghan Markle, a royal author has revealed.

• The foursome stepped out together for the first time since Harry and Meghan moved to the US following the death of Queen Elizabeth II.
• The walkabout was said to be Kate's idea, and Meghan found it very difficult for many reasons.
• In other royal news, Prince William's 'short temper' makes him 'difficult to work with.'

Prince William, Princess Catherine, Prince Harry and Meghan Markle came together as a foursome for the Windsor walkabout following the death of Queen Elizabeth II, where the two couples viewed tributes to Queen Elizabeth and greeted mourners who had gathered outside Windsor Castle.

According to reports, Prince William invited Harry and Meghan to join them - but it was actually Kate who came up with the idea of the walkabout itself, as she didn't want herself or William to 'have any regrets' further down the line.

A friend of Kate's told PEOPLE, "She didn't want her or William to have any regrets." A source also added that for Meghan, the walkabout was very difficult. "That's the longest they had ever been away from the kids, and then on top of it, knowing what's being said out there - it was very difficult," the insider said.

Meghan and Harry had been in Europe for a series of charity appearances without their two children, Prince Archie and Princess Lilibet, who remained in California when Queen Elizabeth died in September. Following the news of the monarch's death, the couple extended their trip to attend the funeral of the Queen.

Similarly, although it may have been her idea, the walkabout was also difficult for Kate, who apparently described it as the 'hardest thing she's ever had to do,' according to the royal biographer, Robert Jobson.

"Sadly, [the united front] was all an illusion - as sources close to the Royal Family have confirmed to me," he said. "Catherine later admitted to a senior royal that, such was the ill feeling between the two couples, the joint walkabout was one of the hardest things she had ever had to do."

The royal author also reminded readers of his book that the walkabout took place before the release of Prince Harry and Meghan's Netflix series and Prince Harry's autobiography Spare. He mused, "If Catherine found it almost unbearable before all this to share a walkabout with the Duke and Duchess of Sussex, then how - one has to wonder - do she and William feel about them now?" 

Princess Kate has also allegedly 'built up resentment' towards Meghan following the death of the Queen. After her death, grandchildren William and Harry were asked not to bring their wives - despite Kate being future Queen Consort.

But the decision to ban both wives from the family moment was reportedly made to stop Meghan travelling to Scotland, and the Princess of Wales wasn't happy about being left out.

Robert Jobson said, "Kate deliberately stayed away, but she desperately wanted to be there with the Queen in her last moments. That’s eaten Kate up and has built up resentment towards Meghan."