The other name in line for the best friend spot is Sophie (seen standing next to Kate in this photo), who has numerous connections within the Cambridges' friendship group. She used to go out with William's best friend Thomas Van Straubenzee, and her brother Robert married one of Kate's school friends Hannah Gillingham. She is always one of the select group to celebrate Kate's birthday with her, and this year when Kate and William attended a church service on the Sandringham estate the following morning with the Queen, Sophie came too. She was also on the skiing holiday William and Kate took with Prince George and Princess Charlotte earlier this year, and is godmother to Princess Charlotte.
Another former Marlborough friend — Trini was Kate's constant companion in London during the year she and William went through their breakup, and in more recent times they have been spotted walking in Kensington Gardens together. Trini was also photographed in the box with Kate when she went to Cirque du Soleil for her birthday. Trini and her husband sat with James Middleton and other members of Kate's family.