The Queen's 90th birthday celebrations started today with a rousing reception at a Royal Mail delivery office.
Cheers greeted the Queen and the Duke of Edinburgh when they arrived at the depot in Windsor - close to the monarch's famous castle home - on the eve of her birthday.
As she met staff at the Queen Elizabeth II delivery office, that has been newly named in her honour, the monarch suggested to Royal Mail Group chief executive Moya Greene that cards and gifts from well-wishers may have added to the huge number of items they deliver every year.
Two choirs made up of Royal Mail staff from London and another group of singers from Bristol sang Happy Birthday to the Queen as she left in bright spring sunshine.
And although the royal birthday is not until Thursday, it did not stop dozens of well-wishers creating a party atmosphere by enthusiastically waving their bunting.
Queen Elizabeth II and Prince Philip visit in Windsor
Jan Warbuton, 60, whose delivers post to staff living at Windsor Castle, was introduced to the Queen.
She said: "When Moya said we deliver over a billion parcels a year, the Queen said 'I've probably added to that this week'."
Windsor delivery office manager Andy Roeton added: "There's a lot of excitement here - we're celebrating 500 years of the postal service, it's the eve of the Queen's birthday and this month I celebrate 25 years with Royal Mail."
The Queen is already Britain's longest reigning monarch, but on her birthday on April 21 she becomes the country's first nonagenarian sovereign.
Her visit to the delivery office on her last day as an 89-year-old saw her commemorate the anniversary of another British institution - the postal service.
Five hundred years ago, in 1516, Henry VIII knighted Brian Tuke, the first Master of the Posts - a move that was the catalyst for the creation of the Royal Mail as it is today.
