The Duke of Cambridge turned 40 on Tuesday, June 21, and marked the day by campaigning for homelessness – a matter of great concern to him. To mark William’s big day, the queen posted an candid snapshot of the smiling Duke with the caption: “As the second in line to the throne turns 40, learn more about His Royal Highness.” The 96-year-old monarch followed suit with eight additional photos taken at various stages during her grandson’s lifetime – each with an insightful account of the Duke. Despite the wishes and congratulations of other members of the royal company, the rift between the two royal brothers seems to continue. A royal source said Kate was trying to encourage the two brothers to settle their differences as the Duke turns 40, saying he believed it would be the “best birthday present ever”. A source close to the family told Closer that the Duchess has been feeling nostalgic for her husband’s birthday, especially since she turned 30 in 2012 on a separate trip to Wales, where Prince Harry and William had a wonderful bond. The expert said that Kate had “quietly sent a message” to Harry and that it would mean a lot to William if he made some kind of contact on his big day. They said: “Kate is a wonderful diplomat and an everlasting optimist. It is certain that one day Harry will escape the ecstasy and become his own man. “If he somehow manages to make the boys make peace – even temporarily – it would be the greatest birthday present William could wish for.” The relationship between the two kings is believed to have begun to deteriorate after William’s concerns about Harry’s rapidly evolving relationship with Megan Markle. READ MORE: Harry and Megan find themselves in a “dead end” with the royals Speaking of her brother’s breakup, royal writer Ingrid Seward said: “Kate has come a long way in encouraging their relationship and although William has always watched Harry, he now feels he can do nothing more. “Instead, he focuses on what he knows he can achieve instead of wasting time on things he can not change. “He knows what lies ahead and knows how difficult it is, but with Kate’s help and the support of his father, the Prince of Wales, he remains positive and optimistic about his future.”