Prince William and Prince Harry's rift is "going to take time" to heal, a royal expert has claimed.The brothers, aged 39 and 36 respectively, put on a united front earlier this month when they reunited to unveil a new statue of their late mother, Princess Diana, on what would have been her 60th birthday. Despite being photographed smiling and talking on the day, it was reported that Harry departed that 20 minutes after the ceremony ended.