Prince Harry and Meghan joined William and Kate to greet mourners at Windsor Castle.
Glamtush reports that the Prince and Princess of Wales, William and Kate, and the Duke and Duchess of Sussex, Harry and Meghan, spent about 45 minutes engaging with crowds of well-wishers and viewing floral tributes in Windsor, before leaving in the same car.
The moment Prince William and Prince Harry walked outside Windsor Castle on Saturday marked the first time the public has seen the two brothers together since the Platinum Jubilee celebrations in June.
The couples spoke to members of the public, accepted flowers and even gave some hugs during the walkabout.
William could be heard thanking people offering their condolences, reading a letter from a little girl out loud, petting dogs and receiving floral bouquets.
Meghan was pictured giving a teenage girl a hug.
CNN reports that Prince William reached out to the Sussexes shortly before the walkabout to extend the invitation, according to a source.