Happy Birthday Queen Elizabeth

Queen Elizabeth (Google/I-Spilled-The-Beans)

Crowds lined the streets in Windsor as the monarch took part in a walkabout, and royal gun salutes have been fired from each of the UK's capital cities. "She's been a very strong female influence," Prince William said on Sky News. "And having lost my mother at a young age, it's been particularly important to me that I've had somebody like the Queen to look up to and who's been there and who has understood some of the more, um, complex issues when you lose a loved one."

On Twitter, the Queen thanked senders of "#HappyBirthdayYourMajesty" tweets.

He said: "We were chasing Zara around who was on a go-cart, and Peter and I managed to herd Zara into a lamppost. And the lamppost came down and nearly squashed her, and I remember my grandmother being the first person out at Balmoral running across the lawn in her kilt.

The Queen, who was accompanied by the Duke of Edinburgh during her tour in Windsor, was presented with a birthday cake at the Guildhall by the Great British Bake Off champion Nadiya Hussain, who had created an orange drizzle cake with a butter cream and marmalade filling.

Most of the gun salutes were due to be 21 shots - the standard royal gun salute - at locations including Hillsborough Castle, Cardiff Castle, and Edinburgh Castle.

In London, the King's Troop Royal Horse Artillery staged a 41-gun salute at midday in Hyde Park. And the Honourable Artillery Company fired a 62-gun salute across the Thames from the Tower of London at 13:00 BST.

Later in the summer, formal celebrations will be held to mark her "official birthday," culminating with a national service of Thanksgiving at St. Paul's Cathedral and a giant picnic outside Buckingham Palace for 10,000 guests.