With the arrival of a royal baby comes the age-old custom of placing a proclamation of royal birth behind the iron railings of Buckingham Palace.

Even in the fast Twitter-paced age, Palace aides have said the tradition will be adhered to for the Duke and Duchess of Cambridge's first born.

The notice will begin its journey at the Lindo wing of St Mary's Hospital in Paddington, London, where Kate's baby is being delivered.

The brief bulletin, on headed Palace notepaper, confirms the sex of the baby but usually gives little else away other than that the baby has been 'safely delivered' and perhaps the weight.

It used to be hand-written but is now mostly typed and will be signed by the Queen's former gynaecologist Marcus Setchell, who is leading the medical team looking after the Duchess.

The document will be completed soon after the birth and, if events happen in daylight hours, will be taken under police escort through the streets of London to the palace.

Placed in a foolscap-sized dark wooden frame, it will be set on an ornate easel behind the railings, just to the side of the front gates of the Queen's London home for members of the public to read.

But the notice will not be put in place until the monarch and senior members of the Royal Family have been told of the new addition to their family.

When the Queen gave birth to Prince Andrew in 1960, some 2,000 people crowded around the railings as the official confirmation announcing the birth of a son - the Queen's third child - was fixed to the gates by Stanley Williams, the then Superintendent of the Palace.

The names given to royal babies are not usually revealed straight away and the public is often left guessing for several days.

William and Kate could, however, buck the trend and unveil their chosen name immediately.

When Princess Beatrice was born in 1988, it was two weeks before her name was known.

When William was born in 1982, his parents, the Prince and Princess of Wales, waited seven days before deciding upon and announcing his name.

The Prince of Wales's name, however, remained a mystery for an entire month and was only declared ahead of his christening in the Music Room of Buckingham Palace in December 1948.

Royal births are usually celebrated with a Royal Salute of 41 guns.

They are registered in the normal way, although the Home Secretary is required to notify certain officials including the Lord Mayor of London, the Governors of Northern Ireland, the Channel Islands and the Isle of Man.

The Queen's top aide, her private secretary Sir Christopher Geidt, informs Governor Generals overseas.

Town criers will also sound out the news of the birth of the future monarch.

As well as keeping to these traditions, the baby's arrival will no doubt also be officially declared via the monarchy's website, on Facebook and summed up neatly in fewer than 140 characters on Twitter, perhaps including an accompanying hashtag, making this royal baby the first future British King or Queen to have news of their birth tweeted by a royal household.

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