Barack Obama paid a moving tribute to the late Prince Philip following his tragic death aged 99 on Friday 9 April.The former President of the United States took to Instagram and shared a heartfelt post on behalf of himself and his wife, Michelle Obama.READ: Prince Charles comforts Queen after sad death of Prince PhilipSharing a photo of the pair alongside Philip and the Queen during Obama's time in office, he reflected on his first meeting with Philip and gushed about his "grace and