"They were very tense as they walked into that chapel," Nicholl said of the brothers. "As they came out of it, you could see some tension diffused. And I think that was largely down to the Duchess of Cambridge, who made a point of speaking to Harry and when she did that, you can see them visibly relax."
Nicholl continued, "It's always been my understanding that behind the scenes, Kate has tried very hard to forge a rapprochement and act as a peacemaker between William and Harry. She loves Harry. She says that she is the sister that he never had. She has been heartbroken to see them fall out, and I think she is one of the few people, one of the few family members who would actually be able to push the brothers together, which she did in a very subtle way, but was very effective."
Ultimately, Nicholl believes Kate "played quite an important role in getting the brothers to the point where they were able to engage in a conversation, of course, in front of the world's press."
"Everyone was watching," she noted. "The focus of the day was absolutely rightly on the Duke of Edinburgh, this was about bidding him a fitting farewell and no one wanted there to be too much attention on William and Harry and this feud — but inevitably the world was watching."
Harry returned home on April 12, marking the first time he had been back in the U.K. since he left the royal family in 2020. Things have been tense between him and his brother and father, Prince Charles, after he and Meghan Markle dropped some major bombshells during their tell-all interview with Oprah Winfrey, which aired on March 7.
The red-headed royal, who now lives in California, was supposed to come home over the summer, but people were hopeful that he could mend his relationship with his older brother sooner than later.
"That closeness, that thawing of icy relations certainly took place outside the chapel. And I think many people felt a sense of relief," Nicholl said of Harry and William's reunion.
"I saw Harry visibly relax when the Duchess of Cambridge started speaking with him," she added. "There had been so much speculation on whether this funeral procession was going to be what finally solved the feisty relationships between the brothers, and I think they do think that everyone hopes that this is a good start towards some sort of reconciliation."