Kate Middleton's birthday celebrations destroyed by Prince Harry's memoir Spare

Kate Middleton - who will turn 41 on Monday January 9 - is planning big to celebrate her birthday amid fears of being targeted by Prince Harry's memoir Spare which is set to hit shelves very next day of the Princess' big event.

Hours after Princess of Wales' birthday party the royals will also be bracing themselves for revelations in the Duke's memoir, which could mainly target William and Kate. 

Prince George,  Princess Charlotte and Prince Louis' mother usually spends her birthday privately, but last year Kensington Palace shared three very special portraits to mark Kate's birthday.

A well-informed source has revealed that the palace is planning something big to mark the much-adored royal's 41st birthday.