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As the world celebrates the arrival of the royal baby boy, take a look at the special times in pictures - from the traditional acknowledgements to the visitors at St. Mary's Hospital

Just like it did when George was born two years ago, at 12.30pm today the BT tower lit up with the message 'It's a Girl!' to mark the birth of the new baby Cambridge - just in case anybody in London didn't already know.

The Royal Navy are the first to mark the occassion

The Royal Navy are the first to mark the occassion

The Royal Navy were one of the first to pay tribute to the new princess. Sailors standing on the flight decks of HMS Lancaster spelt out 'sister' as seen in this charming image.

The sleeping Princess in her mother's arms

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The sleeping Princess in her mother's arms

The Duke and Duchess leave the Lindo Wing with the Princess

(Image credit: Rex Features (Shutterstock))

The Duke and Duchess leave the Lindo Wing with the Princess

The Duke and Prince George wave to waiting well wishers outside the hospital

(Image credit: Rex Features (Shutterstock))

The Duke and Prince George wave to waiting well wishers outside the hospital

The Duke reasures Prince George outside noisy St Mary's

(Image credit: Rex Features (Shutterstock))

The Duke reasures Prince George outside noisy St Mary's

The 41 gun salute at Green Park in London

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The 41 gun salute at Green Park in London

In tribute to the nation's happy news The King's Troop Royal Horse Artillery fired a 41 gun salute in Green Park, London.

The easel at Buckingham Palace makes the official announcement

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The easel at Buckingham Palace makes the official announcement

The offical announcement of the royal baby girl's arrival was posted on an easel outside Buckingham Palace, just like it was with George.

A town crier announces the news outside St Mary's Hospital

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A town crier announces the news outside St Mary's Hospital

An assistant arrives with the new prince's car seat

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An assistant arrives with the new prince's car seat

A clue that the Duke and Duchess would leave St Mary's Hospital came when an assistant arrived at the Lindo wing with a brand new car seat in tow.

A royal aide carries details of the royal baby's birth

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A royal aide carries details of the royal baby's birth

Ed Perkins, a royal aide, had the responsibility of taking papers with details of the new royal baby from the hospital.

The Duke and Duchess of Cambridge with their son George

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The Duke and Duchess of Cambridge with their son George

Prince William and Catherine greet the waiting crowds after the first birth

(Image credit: Rex Features (Shutterstock))

Prince William and Catherine greet the waiting crowds after the first birth

Prince William takes the reins

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Prince William takes the reins

The Duke and Duchess share a joke with photographers

(Image credit: Rex Features (Shutterstock))

The Duke and Duchess share a joke with photographers

A glimpse of the new royal baby boy

(Image credit: Rex Features (Shutterstock))

A glimpse of the new royal baby boy

Carole and Michael Middleton visit their newborn grandson

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Carole and Michael Middleton visit their newborn grandson

The Middletons were the first visitors to meet the new royal baby boy. Carole Middleton told waiting reporters that the Duke and Duchess of Cambridge and their new arrival were doing 'fabulously' well.

The Middletons were delighted after their visit to see George for the first time

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The Middletons were delighted after their visit to see George for the first time

Carole and Michael Middleton smiled to the world's media after their visit to meet their first grandchild at the Lindo ward at St Mary's Hospital in London. Carole Middleton revealed she had not made any suggestions of what Prince William and Kate should name their firstborn.

Prince Charles arrives for a cuddle with his grandson

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Prince Charles arrives for a cuddle with his grandson

After the Middletons' visit, it was the turn of Prince Charles and Camilla to meet their first grandchild and the third in line to the throne. Earlier in the day Camilla told reporters that Prince Charles is great with children.

Prince Charles and the Duchess of Cornwall wave to the crowds

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Prince Charles and the Duchess of Cornwall wave to the crowds

Prince Charles and Camilla visited Prince William, Kate and their new son for around 10 minutes before departing St Mary's Hospital in London. Prince Charles revealed to the waiting media that the world would 'find out in a minute' when the young couple would introduce their newborn to the world.

The London Eye illuminated for George

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The London Eye illuminated for George

As the nation celebrated the news of the birth of a royal baby boy, the capital's iconic landmarks were illuminated against the night sky . The London Eye lit up in a patriotic trio of red, white and blue in tribute to the Duke and Duchess' new arrival

London's BT Tower marks the arrival of the tiny prince

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London's BT Tower marks the arrival of the tiny prince

One of the tallest buildings in London, the BT Tower echoed the sentiments of the nation by lighting up blue with the message 'It's a boy'.

Niagara Falls turns blue for a boy

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Niagara Falls turns blue for a boy

Wow! Not many new babies receive a welcome like this. The Niagara Falls looked even more beautiful than usual swathed in blue light.

The easel at Buckingham Palace announces the news

(Image credit: Rex Features (Shutterstock))

The easel at Buckingham Palace announces the news

The offical announcement of the royal baby boy's arrival was posted on an easel outside Buckingham Palace, in line with tradition for all royal births.

Royalists revel outside Buckingham Palace

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Royalists revel outside Buckingham Palace

The crowds gathered outside Buckingham Palace on a stormy evening in London to celebrate the arrival of the new royal baby - third in line to the throne.