The latest addition to the Royal Family was today waking up in hospital alongside his proud parents The Duke and Duchess of Cambridge.

William was at Kate's hospital bedside as she gave birth to a son weighing 8lbs 6oz at 4.24pm yesterday.

Mother and baby were 'both doing well', said Kensington Palace, while in a short statement released last night the proud parents said they 'could not be happier'.

News of the birth has already caused a wave of joy to wash over the nation. Today, gun salutes will sound across London as the celebrations begin.

In Norfolk, MPs and Royal Family enthusiasts last night spoke of their delight at the safe arrival of the boy, who will no doubt spend much of his life at Sandringham.

People young and old will be hoping to catch a glimpse of the as yet unnamed boy, who spent last night with his parents at the Lindo wing of St Mary's Hospital in London.

The Prince of Wales, who has become a grandfather for the first time, summed up the feelings of the Royal Family when he described the new arrival as an 'incredibly special moment for William and Catherine'.

William telephoned his family to tell them the good news, speaking personally to the Queen, his father Charles and younger brother Prince Harry.

A Buckingham Palace spokesman said: 'The Queen and Duke of Edinburgh are delighted at the news.'

The new royal baby is third-in-line to the throne. He will be the 43rd sovereign since William the Conqueror if, as expected, he follows reigns by Charles and then William.

The news was revealed shortly after 8pm last night when the Queen's press secretary, Ailsa Anderson, strode out onto Buckingham Palace's forecourt to place the official notice on its ornate stand.

The document had four signatures – first was that of Marcus Setchell, Surgeon Gynaecologist to Queen, who led the medical team that delivered Kate's baby.

Mr Setchell spoke movingly about the baby, describing the Queen's third great-grandchild as a 'wonderful baby, beautiful baby'.

News of the birth was issued in a statement by Kensington Palace at 8.30pm: 'Her Royal Highness The Duchess of Cambridge was safely delivered of a son at 4.24pm. The baby weighs 8lbs 6oz.

'The Duke of Cambridge was present for the birth.

'The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, Prince Harry and members of both families have been informed and are delighted with the news.

'Her Royal Highness and her child are both doing well and will remain in hospital overnight.'

Kensington Palace issued a very brief statement from the Duke who, speaking on behalf of himself and the Duchess, said: 'We could not be happier.'

A smiling David Cameron (pictured) declared the birth 'an important moment in the life of our nation'.

Kate was first admitted to the Lindo Wing just before 6am yesterday in the early stages of labour.

She had planned for a natural birth and experienced at least 10-and-a-half hours of labour before her baby was born. Kensington Palace said it had 'progressed as normal'.

William and Kate's son is the first Prince of Cambridge to be born for more than 190 years.