The Christmas tree outside Southwark Cathedral was lit up on Wednesday night at the end of a special service for the Bankside business community.
The annual service for businesses was led by the Dean of Southwark and music was provided by the cathedral's Merbecke Choir.
The lessons were read by representatives of local organisations including Sara Wood of homelessness charity Broadway, one of the beneficiaries of the Bring a Better Christmas campaign, and Donald Hyslop of Tate Modern who chairs Better Bankside.
At the end of the service the clergy, choir and congregation processed to the south churchyard where after a countdown and a shout of 'let there be light' the illuminations were switched on. The choir then closed proceedings by singing 'Rudolph the Red Nosed Reindeer' in Latin.