As the nation rejoiced at the birth of Prince William and wife Kate Middleton's daughter, the country's tourist hotspots joined in by changing colour last night.
Famous British landmarks, including Tower Bridge, the London Eye and the fountains at Trafalgar Square, turned pink following the birth of the princess.
The BT Tower was the first of the London landmarks to celebrate the baby with the words "It's a girl" written at the top.
It then added: "We're delighted at the news and having gone blue for George, it's only fair!"
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Other landmarks in the capital, such as the fountains at Trafalgar Square, the Golden Jubilee Bridge and the London Eye, went pink for the night, much to the delight of tourists and Londoners.
The celebrations extended to Northern Ireland where the Belfast City Hall changed colour.
Well-wishers and the media got their first glimpse of the newborn as she was brought out of the hospital just after 6pm yesterday.
"Disappointed by news @CityWestminster are turning landmarks pink to celebrate royal baby girl. Not exactly challenging gender stereotypes," a tweet said.
There were cheers from the crowd gathered outside the hospital when the announcement was made. Some had been camping for almost two weeks in anticipation of the birth.
The baby is the first to use the title princess since Princess Eugenie, 25, younger daughter of Prince Andrew. The last Princess of Cambridge was Princess Mary Adelaide, George III's granddaughter, born 182 years ago in Hanover, Germany, and known affectionately as "Fat Mary" because of her large girth.