After Prince Harry happily confessed off-camera that he had only had two hours’ sleep since wife Meghan Markle went into labour, Wills took the opportunity to tease his sibling. The Duke of Cambridge said he and Kate were “absolutely thrilled” and looking forward to seeing the newborn in the next few days “when he’s quietened down”, as they launched a regatta in Greenwich. But he couldn’t resist laughing at his younger brother, just like old times. “I’m very pleased and glad to welcome my own brother to the sleep-deprivation society that is parenting,” he said, drawing a smile from the Duchess of Cambridge, who looked in high spirits in a striped top and black pants. “We’re absolutely thrilled – welcome to the Sleep Deprivation Society!” — The Duke of Cambridge on his and The Duchess’s delight at the birth of The Duke and Duchess of Sussex’s son pic.twitter.com/3sTvDL14Cr— Kensington Palace (@KensingtonRoyal) May 7, 2019 “With Louis and Charlotte just having had their birthdays it’s such a great time of year to have a baby, spring is in the air,” she said. William laughed that he would have “plenty of advice” for the new parents, but added, “no, I wish him…