Three things to know as Duke and Duchess of Cambridge welcome 3rd child

LONDON— Like everything to do with the U.K. royal family, a mix of tradition and modernity governed the birth of Prince William and Kate’s third child. Here are three things to know about the U.K.’s royal births:

From palace to hospital

For generations, it was the custom among royals — as among commoners — to give birth at home. Queen Elizabeth II was born at her grandfather’s London house, and gave birth to her sons Charles, Andrew and Edward at Buckingham Palace. Her only daughter, Princess Anne, was born at Clarence House, another royal residence. That changed by the 1980s, when Princess Diana had sons William and Harry at the private Lindo Wing of St. Mary’s Hospital in London. William and Kate’s three children were born at the same hospital.

Delivery-room interlopers

For decades, and for reasons that remain unclear, custom dictated that government officials should be present when a royal was born. Some believe it was to verify that there was no switching at birth or other shenanigans. When the Queen was born in 1926, the U.K.’s home secretary was present among the doctors. The custom was eliminated before the birth of the Queen’s first child, Prince Charles, in 1948.

A formal announcement

News of the newborn prince’s birth was announced by Kensington Palace by email and on Twitter, but it also involved a tradition dating back at least to the 19th century. A messenger travelled by car from the hospital to Buckingham Palace, carrying a piece of paper signed by doctors detailing the infant’s gender, weight and time of birth. Two uniformed palace staff placed the framed notice on a ceremonial easel in the palace forecourt, where it will stay for about 24 hours.