The royal baby has been born on patriotic St George’s Day, which celebrates the patron saint of England.
St George is heralded for his honour, bravery and gallantry.
Surrounded by myth, one legend tells of St George’s slaying of a dragon.
The baby already has an older brother George and Prince Harry and Meghan Markle are set to marry in St George’s Chapel in Windsor next month.
Under Labour’s proposals St George’s Day would become a UK-wide public holiday.
Jeremy Corbyn is pressing ahead with plans to introduce new national holidays to mark the patron saints of England, Wales, Scotland and Ireland, if it wins the next general election.
The actual St George was born in Cappadocia – an area now in Turkey – and he lived during the 3rd century.
He became a Roman soldier and protested against Rome’s treatment of Christians, was imprisoned and eventually executed for refusing to denounce his faith.
The flag of Saint George – a red cross on a white background – is the flag of England and is incorporated into the Union Jack.
April 23 is also the day Edward III founded the Order of the Garter, the senior order of chivalry in England, in 1348.
Each year in June, royals who are Knights and Ladies of the Garter process in carriages to St George’s Chapel in Windsor for the traditional Order of the Garter ceremony.
They dress in their Garter robes – heavy blue velvet capes and black velvet hats with elaborate white ostrich plumes.
The royal baby also shares his birthday with Lady Gabriella Windsor – the daughter of Prince and Princess Michael of Kent, who was also born at the Lindo Wing on April 23 in 1981.
Famous names celebrating their birthdays on Monday include actors Lee Majors, James Russo, John Hannah and Dev Patel; actress Judy Davis, singer Taio Cruz, and model Gigi Hadid.
The baby has just missed arriving on the Queen’s 92nd birthday which was on Saturday.
William and Kate are set to celebrate their seventh wedding anniversary on April 29, while Princess Charlotte turns three on May 2.
Here are some other historic events which took place on April 23:
1564: William Shakespeare, English playwright, poet and actor, was born in Stratford-upon-Avon. He died on the same date in 1616.
1661: Charles II of England, Scotland and Ireland was crowned king at Westminster Abbey.
1775: Joseph Mallord William Turner, English landscape painter, was born in London.
1915: Rupert Brooke, English poet, died of blood poisoning on the Greek island of Skyros.
1927: Cardiff City beat Arsenal 1-0 in the FA Cup Final to become the first club to take the cup out of England.
1968: The first decimal coins appeared in Britain. They were the 5p and 10p pieces which replaced the old one shilling and two shilling coins.
1983: Cliff Thorburn scored the first televised maximum break of 147 in the World Snooker championships, at the Crucible Theatre, Sheffield.
1984: The United States announced the discovery of the Aids virus.
2005: The first video was uploaded to YouTube.com.