By Russell Myers The Princess of Wales delivered a Mother’s Day treat with a picture showing her happy and relaxed that will come as a relief to royal fans worried about her health. In Kate’s first official photo since her abdominal operation in January, she thanked well-wishers who have rallied round her as she recovered at home. The beaming 42-year-old is shown with chuckling George, 10, Charlotte, eight, and five-year-old Louis. It is hoped the snap will finally put an end to the cruel conspiracies theories about the Princess’s health and absence churned out by online cranks, which Kensin…