The Princess of Wales has a very close relationship with her parents and siblings, and no doubt she will have marked her sister Pippa Matthews' birthday on Friday.
Pippa celebrated her 41st birthday on 6 September and has been by her big sister Kate's side through some of her biggest ups and downs in her life.
She has been part of the Princess' support network as Kate continues her cancer treatment, and joined her sister and niece, Princess Charlotte, at the men's Wimbledon final in July.
Pippa looked on proudly as Kate was given a standing ovation by the crowd on Centre Court as she took her seat in the Royal Box.
The author and columnist, who is just 18 months younger than Kate, shared a flat with the future royal in Chelsea, London before Kate married Prince William in 2011.
And at the royal wedding, Pippa was by Kate's side as her maid of honour, turning heads in a fitted dress by Sarah Burton for Alexander McQueen.
Kate was then on hand to support Pippa on her wedding day to hedge fund manager and former racing driver, James Matthews, in May 2017.
The then Duchess of Cambridge was seen smoothing down Pippa's veil as she arrived at the church with their father, Michael Middleton.
Kate also guided the young bridal party into the ceremony, which included her eldest children, Prince George and Princess Charlotte.
Pippa and James have since become parents to Arthur, five, Grace, three, and two-year-old Rose.
The couple swapped their Chelsea townhouse for a £15 million Georgian mansion just 20 minutes away from Bucklebury Farm Park in 2022, close to where Kate, Pippa and their younger James Middleton grew up.
Pippa's husband, James, purchased the 72-acre farm in 2021 for £1.5 million, with the land including a farmhouse-style lodge, which can be rented for events.
Born on 6 September 1983 at the Royal Berkshire Hospital, Pippa educated at St Andrew's School in Pangbourne, before moving to Downe House School and then Marlborough College, where she held a sports/all-rounder scholarship.
She then obtained an English degree from the University of Edinburgh, later earning her postgraduate master's degree in Physical Education, Sport and Physical Literacy from University of Wales Trinity Saint David.
Pippa also released her book with party-planning tips, Celebrate, in 2012 and previously penned a column for Waitrose Kitchen magazine.