Britain's Queen Elizabeth celebrated her 90th birthday today (21.04.16) with thousands of people at Windsor Castle.

Britain's Queen Elizabeth

Britain's Queen Elizabeth

The monarch opted for a bright spring green outfit and matching hat as she and her husband, the Duke of Edinburgh, met with well-wishers outside her country retreat in Windsor, Berkshire.

Many bought gifts of flowers, cakes and cards, which they handed over to the Queen and her aides, and they were treated to a performance of Happy Birthday by the Coldstream Guards as she arrived at the castle.

At the event, Her Majesty was presented with her birthday cake, made by 'The Great British Bake Off' winner Nadiya Hussein.

The beautiful creation - which featured both purple and yellow icing - was an orange drizzle cake complete with butter cream or marmalade filling.

Following their walkabout around the crowds gathered at Windsor Castle, the Queen and Prince Philip were driven through the streets of Windsor in an open top Land Rover, where they waved to excited locals.

Terry Hutt and Margaret Taylor camped overnight to ensure they got the best spot.

Margaret said: "I gave her a birthday cake. I had to give it to her lady-in-waiting as it was so heavy, which amused the Queen."

Whilst Terry added: "I told her she looked younger than ever and she smiled and said 'Thank you.'"