CONGRATULATIONS are pouring in for Kate and William after they became parents for the first time following the birth of their son, the new third in line to the throne.

The announcement at about 8.30pm came after a day of frenzied activity outside the London hospital involving hundreds of journalists and well-wishers who had been awaiting news since the duchess was driven to the hospital at 5.30am.

A statement from Kensington Palace, which was put up by a footman outside Buckingham Palace, read: "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."

William phoned his family to tell them the news, speaking personally to the Queen, his father Charles and younger brother Prince Harry. The Duke of Cambridge issued a statement last night, saying: "We could not be happier."

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

David Cameron said: "It is wonderful news from St Mary's, Paddington, and I am sure right across the country, and indeed right across the Commonwealth, people will be celebrating and wishing the royal couple well."

The Prime Minister added: "It is 
an important moment in the life 
of our nation but above all it is a 
wonderful moment for a warm and loving couple who have got a brand new baby boy.

"The whole country will celebrate. They'll make wonderful parents."

Prince William's father, Prince Charles, said both he and wife, Camilla, were "overjoyed at the arrival of my first grandchild". He added: "It is an incredibly special moment for William and Catherine and we are so thrilled for them on the birth of their baby boy.

"Grandparenthood is a unique moment in anyone's life, as countless kind people have told me in recent months, so I am enormously proud and happy to be a grandfather for the first time and we are eagerly looking forward to seeing the baby in the near future."

First Minister Alex Salmond added: "I am sure people across Scotland will be thrilled to hear the news of the birth of a baby boy to the royal couple and will want to join me in wishing the proud parents many congratulations."

The Queen's former gynaeoclogist Marcus Setchell, who led the team that delivered the boy, said "wonderful baby, beautiful baby" as he left the Lindo Wing. Also involved was Alan Farthing, gynaecologist and ex-fiance of murdered TV presenter Jill Dando.

The notice, signed by Mr Setchell, was driven by car from the hospital where it was placed on an easel in Buckingham Palace's forecourt in a similar fashion to the announcement of William's birth in 1982.

Labour leader Ed Miliband added: "Many congratulations to the Duke and Duchess of Cambridge."

From the US, President Barack Obama said: "We wish them all the happiness and blessings parenthood brings. The child enters the world at a time of promise and opportunity for our two nations."

William and Kate, who are the Earl and Countess of Strathearn and met while studying at St Andrews University, told well-wishers she was hoping 
for a boy. A university spokesman said: "We offer the couple our warmest congratulations."

The baby's uncle, Prince Harry, now moves to fourth in line to the throne, while the Duke of York shifts down to fifth and Princesses Beatrice and Eugenie to sixth and seventh place.