The Queen and the Duke of Edinburgh will not attend the christening of Prince Louis later today.
Buckingham Palace said the decision was taken by the Queen and the Duke and Duchess of Cambridge "some time ago" and it is not due to health reasons.
Prince Louis will be christened in a private ceremony in the Chapel Royal at St James's Palace.
The 11-week-old will be baptised by the Archbishop of Canterbury, the Most Reverend Justin Welby.
The ceremony will be the first time the Duke and Duchess of Cambridge and their three children have been seen together.
The Queen, 92, is travelling back from Norfolk on Monday and has a busy week ahead, with celebrations marking the centenary of the RAF on Tuesday and US President Donald Trump's visit to Windsor on Friday.
Prince Louis' six godparents are Nicholas van Cutsem, Guy Pelly, Harry Aubrey-Fletcher, Lady Laura Meade, Mrs Robert Carter and Lucy Middleton.
They are all friends or family of the Cambridges, who also picked friends and confidantes as Prince George's and Princess Charlotte's godparents.
Newlyweds the Duke and Duchess of Sussex will attend the ceremony, along with Kate's pregnant sister Pippa Middleton and their brother James Middleton. Prince Louis' grandfather, the Prince of Wales, and the Duchess of Cornwall will also attend the ceremony.
Prince Louis will wear the same christening gown used by his siblings.
The cream lace and white satin robe is a replica of the robe made for Queen Victoria's eldest daughter in 1841, which is now too delicate to be worn. The new version was made by the Queen's dresser, Angela Kelly.
Media captionPrince George was carried into the Chapel Royal by his father, the Duke of Cambridge
According to tradition, water from the River Jordan will be used.