A plaque explaining the role of the 2,500 volunteers from Britain and Ireland who fought for the republicans in the Spanish Civil War has been unveiled in Jubilee Gardens on the South Bank.
On the first Saturday in July each year the International Brigades Memorial Trust holds a commemoration event at the memorial sculpture which has stood on the South Bank since 1985.
An explanatory plaque has been set into the paving at the foot of the memorial.
The plaque was unveiled by 93-year-old David Lomon who is one of only three surviving British veterans of the 1936-39 conflict in Spain. He was living in Hackney when in 1937 he decided to join the International Brigades.
After travelling clandestinely through France, he crossed the Pyrenees and saw action in Aragon where he was captured with other members of the British Battalion. He then spent six months in prison camps in San Pedro de Cardeņa, near Burgos, and Palencia.
Almudena Cros, representing the Spanish Association of the Friends of the International Brigade, known as the amigos, presented David Lomon with a Republican flag inscribed with his name.
Taking part in the ceremony were folk musician Ewan McLennan who led the singing of Jarama Valley and performance poet Francesca Beard who read two specially composed poems. The Na-Mara folk duo and Spanish singer-songwriter Paco Marin also gave short performances.
Included in the list of names read out of those who had died during the last year were Fritz Teppich, the last German anti-fascist volunteer, and Nathan Clark of Clarks Shoes who invented the desert boot.
Wreaths were laid by several organisations including the Spanish Embassy, ASLEF Waterloo Nine Elms branch and the TGWU trade union Parliamentary branch.
The large crowd included Lambeth Pensioners Action Group representatives.
Also present was former trade union leader Rodney Bickerstaffe who called on young people to join the International Brigades Memorial Trust.