The party had originally been planned for July 1, when the brothers unveiled a statue of Diana, Princess of Wales, on what would have been her 60th birthday
Since attending the statue’s unveiling, Harry has announced he is writing his memoirs. They are due for release next year, when the Queen will celebrate her Platinum Jubilee to mark 70 years on the throne.
An insider said: ‘The delayed party had initially been planned for September, but it was put back again as they had to check diaries.’
Last night a spokeswoman reportedly confirmed that the Sussexes would not be coming. It will be seen as a sign of the growing rift between the brothers.