THE Queen has celebrated her 90th birthday by greeting well-wishers outside Windsor Castle.

Hundreds of royal fans cheered the monarch as she stepped from her car in front of the Henry VIII gate.

Her arrival was marked by a rendition of Happy Birthday by the Band of the Coldstream Guards.

Born Princess Elizabeth Alexandra Mary of York on April 21 1926 - the year of the General Strike - she was never expected to be Queen.

But she has become the longest reigning and oldest monarch in British history - and now the first to reach 90.

The Queen spent the morning of her birthday in private at her much-loved Berkshire castle - the family home of the nation's sovereigns for more than 1,000 years.

She went on to mark her special day by carrying out public duties, including opening a walkway created in her honour and carrying out a walkabout through Windsor town.

Hundreds of royal fans, waving flags and clutching flowers, packed the streets to catch a glimpse of the birthday Queen.

She was accompanied by her husband of more than 68 years, the Duke of Edinburgh, who himself turns 95 in June.