The Queen was joined by her daughter Princess Anne at the national service to commemorate the 100-year milestone.
The Royal British Legion has been a lifeline to the nation’s armed forces, veterans and the wider military family.
Retired Lieutenant General James Bashall, the RBL’s national president, said the centenary was a “very proud moment” for all those associated with the legion and it was an honour to have their patron the Queen and Princess Anne as guests as the service.
There was a great atmosphere around Westminster Abbey today and I thoroughly enjoyed talking to veterans and their families.
General Sir Nick Carter, Chief of the Defence Staff, was among the congregation for the service and the outgoing head of the armed forces was joined by members of the military, veterans and their families from the UK and the Commonwealth.
RBL supporters, volunteers and partner organisations were also sat in the pews for the service led by the Dean of Westminster Dr David Hoyle.
Readings were given by Colour Sergeant Johnson Beharry, Sir Nick and Sara Jones, whose husband Lieutenant Colonel Herbert “H” Jones was awarded a posthumous Victoria Cross for his bravery at the Battle of Goose Green during the Falklands Conflict.
Princess Anne also gave a scripture reading on the theme of service, and there was a rededication from the RBL’s national president, reaffirming the legion’s commitment to its work.