Prince William and Kate Middleton concluded their royal train tour by joining Queen Elizabeth II, Prince Charles, Camilla, Duchess of Cornwall, Prince Edward, Sophie, Countess of Wessex, and Princess Anne in the quadrangle of Windsor Castle.The group -- who maintained six feet of separation throughout the event — was gathered to thank local volunteers and essential workers amid the ongoing COVID-19 pandemic.The royal family enjoyed a performance by The Salvation Army UK band, before William and