Prince Harry’s decision not to attend Princess Diana’s memorial party could drive a further wedge between him and his brother William, according to a royal expert. Celebrities, dignitaries, family and friends of Diana are gathering today to honour the late princess at Kensington Palace in what would have been her 60th year.The event was originally due to be held in the summer to thank donors for helping to fund the commemorative statue of Diana in the grounds of the palace.