The church of St Mary Magdalene is seen on the Sandringham Estate, Norfolk. Princess Charlotte, the daughter of Britain's Prince William and Catherine, Duchess of Cambridge will be christened at the church. REUTERS/Joe Giddens/Pool

The christening of Princess Charlotte will be remembered for two major departures from the normal.

It will see some of the Crown Jewels leave London for the first time in 175 years in a top secret operation. The baptism will also be the first one open to public.

The Lily Font, made of gilded silver and used for the baptisms of almost every royal baby since commissioned by Queen Victoria in 1840, will hold the water from the River of Jordan where Christ is believed to have been baptised.

It will be poured from a silver ewer made in 1735 for the christening of George III.

Kept at the Tower of London, the Lily Font weighs more than 21lbs (10kgs) and stands 17in high (43cm). The bowl is a large, open lily bloom, decorated with lilies, ivy and cherubs. It is only used for royal children who are entitled to an HRH title.

The ewer is a tulip-shaped pitcher with a handle topped by a figure of Hercules holding a large club and slaying the hydra.

The second child of William and Kate, the Duke and Duchess of Cambridge will be baptised by the Archbishop of Canterbury at 4.30 pm at The Church of St Mary Magdalene on the Queen's estate in Sandringham in Norfolk, where the family attends the annual Christmas service.

It is the same church where Prince William's mother, Princess Diana, was christened.

Royal christenings have mostly been held in palaces away from public view. This time around it has been opened to public who can view it from the paddock next to the church arranged by Prince William and Kate.

The public will be allowed take souvenir pictures and "selfies" at the christening.

Exclusive guest list

The exclusive guest list includes the Queen, the Duke of Edinburgh, the Prince of Wales and the Duchess of Cornwall, along with Kate's parents, Carole and Michael Middleton. Prince Harry will not attend as he is currently in Africa.

Princess Charlotte will wear the same christening robe as Prince George which is a replica of one made in 1841 for the christening of Queen Victoria's eldest daughter, Victoria, Princess Royal.

Charlotte, who is fourth in line to the British throne after her grandfather, Prince Charles, her father Prince William and brother Prince George, was born at St Mary's Hospital in London on 2 May.

Prince George and Princess Charlotte are seen in this undated handout photo taken by the Duchess in mid-May at Anmer Hall in Norfolk and released by the Duke and Duchess of Cambridge REUTERS/Duchess of Cambridge/Handout via Reuters