The future King engaged young Mason Harrison about his flag-waving skills when he caught the VIP’s eye in the crowds gathered on Carrickfergus seafront.
William joked with the two-year-old who also enjoyed a ‘high five’ with Kate.
Mason’s mum Gemma Champion said: “The prince held his hand and said ‘oh you brought a flag’ and said he'd a ‘very tight grip’. He also got a high five off Princess Catherine.
"What a fantastic day for Carrickfergus.”
Another stand-out image was the one of the Princess of Wales with Isaac Railton in her arms during her visit to youth charity Carrickfergus Connect.
Proud grandad Iain Railton said: “Isaac is two months old. He was with his mummy, Shannon Railton, my daughter and they met the royals in the Yoga Loft in Carrickfergus with other young people from Carrickfergus Connect.”