Transport chiefs joined war veterans for a memorial ceremony and vintage bus ride on Monday to mark the centenary of Britain's entry into the First World War.
WWII veterans from London Transport Old Comrades' Association met Transport for London (TfL) boss Leon Daniels at the Merton Bus Garage in Morden.
Bus garage staff and veterans laid wreaths at the centre, chosen by TfL as one of several transport memorials to remember the many transport staff who helped win the war.
Around 1,000 London buses were used as ambulances and to transport men to the front.
A TfL spokesman said: "you had bus drivers who were going from Shepherd Bush to Raynes Park and then two weeks later found themselves driving that same bus all along the western front and be there for four years.
"It's quite a remarkable story and what's fascinating is the fact that these humble buses played this role that nobody really thought about."
A 1911 B-type bus No. B43, 'Ole' Bill', was loaned by the Imperial War Museum for the veterans' excursion yesterday.
One of the first buses to be requisitioned during the war, it was refurbished afterwards as a permanent memorial to the role played by London bus staff.
On Februrary 14, 1920, the bus was inspected by King George V at Buckingham Palace, the first time the King had boarded a bus.