Hundreds of St John Ambulance volunteers have marched in an annual parade to mark the charity's achievements over the past year.
Volunteers were among the first on the scene on 7 July
This year's event took on special significance as it focused on the work they did in the aftermath of the 7 July 2005 bombings in London.
A band led members from Smithfields in the City of London to St Paul's Cathedral on Saturday.
Some 42,000 volunteers helped more than 132,000 people in the UK in 2005.
Saturday's procession included Seamus Kelly, the St John Ambulance commissioner for London, who was responsible for co-ordinating the volunteers on 7 July.
First on scene
Following the first explosion, London's major incident plan kicked in and St John Ambulance was asked to mobilise.
Some of their members were first on the scene and worked closely with the ambulance service.
Volunteers also provided care and support to casualties at the main sites and ambulance transport.
They were present at mobile treatment centres for a further five days until the emergency was over.
"Every day we teach first aid, and every day our volunteers give first aid help to those in need, regularly saving people's lives," said Sir Brian Jenkins, from St John Ambulance.