In a break from expected protocol, Kate and William asked the Middletons to visit them and their new child before any members of the royal family, including Prince Charles, who is on a royal visit to York.
The Middletons arrived in a black cab and were greeted by the hospital's lead clinician Jonathan Ramsay.
The Duke and Duchess of Cambridge have thanked hospital staff at St Mary's Hospital for their help and support – and are preparing to take their new son home.
Kate's Gynaecologist Marcus Setchell and her hairdresser have both arrived at St Mary's, fuelling speculation that the new family will leave hospital today.
The Duke and Duchess are expected to leave via the front door with the new Prince of Cambridge, who has yet to be named.
The new parents released a statement earlier today thanking hospital staff for their care.
It read: "We would like to thank the staff at the Lindo Wing and the whole hospital for the tremendous care the three of us have received. We know it has been a very busy period for the hospital and we would like to thank everyone – staff, patients and visitors – for their understanding during this time."
A spokesperson from Kensington Palace added: "Mother, son and father are all doing well this morning."
Kate and William have been spending time bonding with their new son.
The new Prince of Cambridge remains unnamed, and it seems even the Royals are in the dark over the couple's name choice!
Speaking to crowds today, new granddad Prince Charles said: "I'm thrilled and very excited," but added he didn't know – or wasn't giving away – the baby's name, telling the BBC: "It's not clear yet."
James – which brilliantly means 'replace'- is the odds-on favourite according to the bookies, closely followed by George. Baby Cambridge is also expected to have several middle names.
Earlier today, Guardsmen outside Buckingham Palace played 'Celebration' for Kate and William, and the King's Troop Royal Horse Artillery and the Honourable Artillery Company carried out a 41-gun salute at London's Green Park and 62 rounds at the Tower of London.
Gun salutes are fired for the birth of every Prince or Princess – the last one was for Princess Eugenie in 1990