A teenager has spoken of his surprise at seeing his own face on a movie poster at a bus stop in south London.
Shiden Tekle was on his way to school when he saw his image in a mocked-up recreation of the poster for The Inbetweeners film.
He had created the image as part of a project highlighting the lack of black roles in the media but said "they were only supposed to go online".
Guerrilla advertisers had, unbeknownst to him, placed them around Brixton.
The posters show black faces superimposed in the lead roles and were recreated by Mr Tekle - who founded activism group Legally Black while at the Advocacy Academy - and his friends.
They were found online by the Special Patrol Group, who put full-sized versions in advertising spaces at bus stops in the capital.
"The first I knew was when I saw a poster of myself at the bus stop," said Mr Tekle.
"It was quite overwhelming actually to see how our project can reach a wider audience."
A 2016 study by the British Film Institute showed that black actors were cast in 0.5% of all lead roles in British films released between 2006 and 2016.
The teenager, together with friends Liv Francis-Cornibert, 18, and 17-year-olds Kofi Asante and Bel Matos da Costa, re-imagined posters for Titanic, Harry Potter and Doctor Who.
"The point was to highlight the lack of authentic black roles in media," said Ms Francis-Cornibert.
"We're not saying you have to remake Harry Potter with black actors, but it highlights the lack of black roles that aren't athletes, drug dealers or a token black friend."
Amelia Viney, founder of the Advocacy Academy, which aims to get students involved in political activism, said she was "extremely proud" of the group.
"The idea that a 17 or 18-year-old can get recognition for fighting for other people is really cool," she said.
The posters were taken down after one day, "but someone stole the Doctor Who posters, which always gives me hope," Ms Viney added.
JCDecaux, the advertising company that owns most of the advertising spaces, has been contacted for comment.