The Duke and Duchess of Cambridge, Prince George and baby Charlotte, who was born at the start of May, will all be seen together for the first time at the event at the Church of St Mary Magdalene in Sandringham, Norfolk, on Sunday.

Guests including the Queen, the Duke of Edinburgh, the Prince of Wales and the Duchess of Cornwall, Kate’s parents Carole and Michael Middleton, other family and Charlotte’s godparents are also expected to attend the traditional ceremony.

Much like the Christmas Day service, members of the public will be allowed to gather nearby to see Charlotte and the royals as they make their way to and from the church.

Today Norfolk Police said that anybody wishing to join the celebrations should arrive in time for gates to the paddock outside the church opening at 3pm. The ceremony is due to start at 4.30pm.

Superintendent Kevin Clarke said: “With this being such a special occasion we are expecting the area to be extremely busy on Sunday and encourage the public to heed our advice so they can enjoy the event safely.”

Car parking will be available but large crowds are expected.

“People are asked to consider their arrival time carefully as they could be queuing for some time in warm temperatures with limited refreshments and facilities in the area,” a spokesman added.

Anyone bringing flowers will be asked to give them to representatives of East Anglia’s Children’s Hospices (EACH), where Kate is a patron, who will then take them to hospices in the region.

A Kensington Palace spokesman earlier said William and Kate were “delighted” that the paddock outside the church would be open to well-wishers, and were “hugely grateful” for people’s warm wishes since the birth of their daughter.

“While the service inside the church will be private, The Duke and Duchess of Cambridge will be pleased to welcome well-wishers into the paddock outside the church,” the spokesman said.

“The Duke and Duchess are hugely grateful for the warm wishes they have received since Princess Charlotte’s birth - many of them from local people in Norfolk - and are delighted the paddock can be opened on the day of the christening.”

The Archbishop of Canterbury, the Most Rev Justin Welby, will conduct the ceremony and give an address. He will be supported by The Reverend Canon Jonathan Riviere, the Rector of the Sandringham group of parishes.