Chatting on a mobile phone in front of Westminster Cathedral, Colin Firth went almost unnoticed.
Shoppers and tourists flocked past as The King's Speech star worked on scenes for his latest film.
Dressed in a nondescript grey suit, a pair of glasses and with ruffled hair, few appeared to recognise the A-list star standing next to a newly-assembled flower stand.
Many ignored him entirely, taking pictures of the London landmark instead.
But some onlookers - drawn by the sight of cameramen and security guards - paused to watch the 50-year-old as he ran through his lines.
Behind him, crew members hosed down an area in front of the cathedral, creating the impression of recent rain.
Colin, who was recently awarded a CBE for his Oscar-winning performance as stuttering monarch King George VI, is starring opposite Cameron Diaz in a remake of 1966 crime caper Gambit.
In the new version, scripted by Joel and Ethan Coen, he plays a London art curator who tries to con a wealthy collector into buying a fake Monet painting.
Cameron stars as a Texan rodeo worker who is roped into the plot.
The original version - with Sir Michael Caine and Shirley MacLaine - was nominated for three Oscars.