A "Buy More Pointless Stuff" billboard that appeared in Ealing is the work of an "organised artistic crime" artist with more than 13,000 followers on Instagram.
The boards, in The Vale, Uxbridge Road, neatly display the message "Buy More Pointless Stuff" and sparked a huge online discussion on social network site reddit.
At one point, it was the most talked-about topic in London on Friday (February 12) on the site.
One user commented: "Who let the sixth formers put billboards up?"
But now getwestlondon can confirm that the billboard was put up by a street artist by the name of "MOBSTR".
The artist, who calls the work "Organised Artistic Crime", has 13,800 followers on an Instagram account which currently features 92 of the artist' posts.
"MOBSTR" also has a website which, in addition to Instagram, appears to show similar art across London.
Here is some more of the artist' work: