Royal baby video: Duchess of Cambridge leaves hospital with baby son - FIRST LOOK footage

The Duchess of Cambridge appeared in good health wearing a beautiful red dress, holding the Royal baby boy joined by Prince William as they presented the new member of the Royal family to the world.

Prince William was by his wife’s side when their royal baby was delivered by staff at the London hospital.

He later left St Mary's Hospital to pick up Prince George and Princess Charlotte to let them meet their baby brother.

Confident Princess Charlotte adorably waved at the crowd as she arrived at the Lindo Wing of the London hospital with her brother Prince George. 

The Royal siblings later returned home after meeting their newborn baby brother.

As he left, the Duke told reporters he was "very happy, very delighted, thank you".

He added: "Thrice the worry now."

And to reporters, he said: "We didn't keep you waiting too long this time."

The Duchess of Cambridge gave birth to a baby boy after being admitted to the Lindo Wing at St Mary's Hospital earlier on the morning of April 23.

Kensington Palace confirmed the news on Twitter, writing: "Kensington Palace tweeted: “Her Royal Highness The Duchess of Cambridge was safely delivered of a son at 1101hrs.

“The baby weighs 8lbs 7oz.The Duke of Cambridge was present for the birth.

“Her Royal Highness and her child are both doing well.”

All of three of the Duchess of Cambridge's children have weighed more than 8lbs.

But the new prince is not the heaviest royal baby in recent years.

That title falls to Savannah Phillips - the daughter of the Queen's grandson Peter Phillips - who weighed 8lb 8oz in 2010.

Prince William weighed 7lb 1.5oz in 1982, while Prince Charles weighed 7lb 6oz in 1948.

Prince Harry weighed 6lb 14oz in 1984.

The newest arrival is the royal couple’s third child and will be welcomed by big brother Prince George, four, and two-year-old sister Princess Charlotte.

The royal baby will be the fifth in line to the British throne, pushing uncle Prince Harry into sixth place.

Many have been eager to know what the couple plan to name the third Royal Baby.

Arthur is the 5-1 favourite with Coral in the betting on the name of the new baby, Mary can be backed at 6-1, while Alice is 7-1.

The firm makes a boy the odds-on favourite at 10-11 in the gender betting, while a girl is evens.

Leading bookmaker Coral has again slashed the odds on Prince William and Kate naming their third child James to 8-1, having been 16-1 around a week ago, with the birth expected any day now.

Jessica Bridge of Ladbrokes said: "As all attention turns to the Lindo Wing the betting is still incredibly tight, and the recent gamble on Kate giving birth to a little boy means fingers are pointing towards Prince Arthur soon entering the world."