What are the traditions for a British royal birth?

Prince Harry and Meghan are a modern couple but their first-born child will still be a senior royal. And certain traditions must be respected.

There was a time the home secretary, Britain's interior minister, would have been expected to witness the birth of potential heirs to the throne -- and the new arrival is seventh in line.

Fortunately for Meghan, who gave birth early on Monday, this tradition ended after the birth of the queen's cousin, Princess Alexandra, in 1936.

The public announcement was made on Instagram but Queen Elizabeth II and senior royals would have been the first to be informed.

The family also followed tradition and issue a proclamation signed by royal doctors displayed on an ornate easel in the forecourt of Buckingham Palace.

According to precedent, a cannon is set to be fired across London in celebration and the Union Flag will be flown from government buildings across Britain.

The traditional 21-round gun salute has 20 more rounds if fired from a royal park or palace, and a further 21 from the Tower of London because of its location in the City of London.

All births in England and Wales, regardless of parentage, must be registered within 42 days at the hospital or a local register office.

Home Secretary Sajid Javid will notify the Lord Mayor of London, while the queen's private secretary informs her governor-generals, her representatives in the 15 other Commonwealth realms where she is head of state.

The baby's name was not revealed right away -- Prince Harry said this could happen on Wednesday.

Of William's children, George and Charlotte were named after two days, while Louis' name took four days.

The new baby's title has also not been announced but, unlike William's children, it will not be a prince or princess.

As a boy, the baby could be styled as the Earl of Dumbarton, taking Harry's most senior subsidiary moniker as a courtesy title.

Barring a change in the rules, the baby would only be entitled to the prefix of his royal highness (HRH) upon Charles, the heir to the throne, becoming king.

The baby will be christened as a member of the Church of England, wearing a 2008 replica of the intricate lace and satin gown made for queen Victoria's eldest daughter in 1841. Sixty-two royal babies wore the original.

Like the original, the new robe has a long skirt, elaborate collars and bow. By tradition, new royal babies are baptised by the Archbishop of Canterbury with water from the River Jordan poured into the traditional silver Lily Font, which is part of the crown jewels.

Royal babies usually have around six godparents, people who agree to support the child, particularly in their faith.