The Queen, The Duke of Edinburgh, and members of the Royal Family attend a National Service of Thanksgiving at St Paul's Cathedral, before The Queen, The Duke, The Prince of Wales and The Duchess of Cornwall host visiting Governors-General for lunch at Buckingham Palace.
Also following the service, The Duke and Duchess of Cambridge and other Members of The Royal Family met guests from the service at the Guildhall.
The Queen and The Duke of Edinburgh were joined by members of the Royal Family of a National Service of Thanksgiving at St Paul's Cathedral, on the first of three days of events marking Her Majesty's 90th Birthday.
Prayers at the service were led by people representing aspects of Her Majesty's life and role. Sir David Attenborough read Paddington Bear creator Michael Bond's personal account of growing up to be 90.
We look back on Your Majesty's 90 years in the life of our nation with deep wonder and profound gratitude
Justin Welby, Archbishop of Canterbury
It was one of three birthday gifts featured in the ceremony for the monarch, and brought laughter from the congregation.
Following the Service at St Paul's, The Queen hosted a lunch at Buckingham Palace for all of her Governors-General from the Commonwealth Realms.
The Duke of Edinburgh, The Prince of Wales and The Duchess of Cornwall joined Her Majesty to greet the Governors-General to Buckingham Palace.
The Duke and Duchess of Cambridge, and members of the Royal Family gathered with 1,800 guests at London's Guildhall for an after-service reception, where the Lord Mayor of London paid tribute to The Queen.
It is certainly with gentleness, good humour and understanding that, against the shifting sands of societal change, Her Majesty so wonderfully exemplifies the advantages of a constitutional monarchy
Jeffrey Mountevans, Lord Mayor of London
Following the Lord Mayor's speech, members of the Royal Family met guests from the St Paul's Service.