“It´s only advertising” is the title of Keaton Henson´s blog post where he shows off the video of painting these words (but I´m sharing it this despite that).
I walked past the wall the other day where they´re on a massive poster near Old Street and took a photo because I liked the question. I think love should make your head spin a bit.
Wasn´t sure where they came from but turns out it´s the lyrics of a song. This song. Which is quite nice.