British monarch Queen Elizabeth II is celebrating her 80th birthday today (21APR06), and she has spoken of her joy at receiving thousands of cards and messages from all over the globe. The Queen was sent 20,000 cards and 17,000 emails from her admirers, despite choosing to celebrate quietly with her family, away from the public gaze. She gave the following special message to the public: "I would like to thank the many thousands of people from this country and overseas who have sent me cards and messages on my 80th birthday. "I have been very touched by what you have written and would like to express my gratitude to you all for making this day such a special one for me." Union flags will be flown across the UK until sunset, and in London a 41-gun Royal Salute will be fired by the King's Troop Royal Horse Artillery in Hyde Park. The Queen's son Prince Charles will be giving a three-minute broadcast in his mother's honour, which will be aired on BBC Radio 4 at 5pm (BST) and screened on BBC1 and Sky News just before 6pm.