Video report by ITV News Royal Editor Tim Ewart
Queen Elizabeth has attended a national service of thanksgiving to celebrate her 90th birthday at St Paul's Cathedral.
She arrived with Prince Philip to kick off of a weekend of celebrations marking the milestone.
Members of the Royal Family and senior government figures, including Prime Minister David Cameron and former prime minister Tony Blair, went to the service of thanksgiving for the monarch's life.
The Duke of York and his daughters Princess Beatrice and Princess Eugenie attended and the Duchess of Cambridge wowed the crowds in an outfit by Catherine Walker and a hat by Jane Taylor.
The Duke and Duchess of Cambridge make last-minute checks as they arrive with Prince Harry:
Hundreds of ordinary people recognised for their service gathered to mark the Queen's 90 years.
The service features a sermon by the Archbishop of Canterbury, as well as prayers spoken by a 90-year-old Welsh widow - born on the same day as the Queen.
Sir David Attenborough and Paddington Bear creator Michael Bond, who have both turned 90 this year, are also at the service.
The Queen turned 90 on April 21, but she traditionally has two birthdays and her official birthday will be marked by the Trooping the Colour ceremony tomorrow.
It is Prince Philip's 95th birthday today and will be marked with traditional gun salutes.
Crowds stood around the edge of Sir Christopher Wren's famous cathedral cheered loudly when they saw the royal group step off a coach.
The Queen arrived more than 10 minutes late,because of heavy traffic.