The Prince and Princess of Wales have stepped out together in public for the first time since the Duke of Sussex published his memoirs which laid bare his fraught relationship with the couple.William and Kate looked relaxed as they arrived to officially open the new Royal Liverpool University Hospital in the home city of The Beatles.Harry’s controversial autobiography, Spare, has become the fastest selling non-fiction book in history, according to publisher Penguin Random House, which reported more than 1.4 million copies were sold on Tuesday, the first day it went on sale.