The Duke and Duchess of Cambridge's son Prince George will be christened today in front of close family and friends of his parents.
The three-month-old infant, who will one day be king, will be baptised by the Archbishop of Canterbury, the Most Rev Justin Welby, in the little known Chapel Royal at St James's Palace this afternoon.
The Queen and Duke of Edinburgh are expected to be at the ceremony along with the Prince of Wales, who has become a grandfather for the first time, the Duchess of Cornwall and Prince Harry.
Kate's family - parents Carole and Michael Middleton and siblings Pippa and James - are thought to be invited, along with the godparents who, like the guests, have not been publicly named.
There has been speculation about who the Cambridges might choose to be their son's mentors.
Close friends Hugh van Cutsem and Thomas van Straubenzee are thought to be in the running along with Old Etonian James Meade and interior designer Emilia d'Erlanger, who has known both William and Kate for a number of years.
The royal couple have chosen celebrity portrait photographer Jason Bell to take the official pictures to mark the christening.
Bell is renowned for his images of Hollywood stars and rock and pop legends like Sir Paul McCartney, actress Scarlett Johansson and former England footballer David Beckham.
The photographs taken after the ceremony will be historic images that are expected to capture four generations of the royal family together.
The pictures will show the Queen with three future monarchs - Charles, William and George.
It will echo the picture taken in July 1894 during the christening of the future Edward VIII, showing the royal baby with his father, later George V, grandfather, the future Edward VII, and great grandmother, Queen Victoria.
Bell's images have been featured in the National Portrait Gallery and published in glossy magazines like Vogue and Vanity Fair.
In past decades, senior royal babies - the Queen, Charles and William - have been christened at Buckingham Palace.
But the Cambridges have chosen the Chapel Royal, where the coffin of the Duke's mother, Diana, Princess of Wales, lay before her funeral.
Princess Beatrice was the last well known royal baby to be christened at St James's Palace, in December 1988.
George will be christened in a replica of the intricate lace and satin christening gown made for Queen Victoria's eldest daughter, Victoria, the Princess Royal, in 1841.
The Earl and Countess of Wessex's son, Viscount Severn, became the first royal baby to wear the new robe at his christening in 2008.