The faces started to appear about three months ago.
Huge faces, almost 8ft high.
On hoardings, down litter-choked alleyways, on nondescript streets, in little unloved corners of Glasgow they turned up, usually in sets of two.
Some have disappeared quickly. Others have remained for weeks, even months.
The first, on Sauchiehall Street, is still there. It's a portrait of a young Australian woman called Farrin. She lives in Adelaide. The question is, what is her picture doing in Glasgow?
The answer, it can now be revealed, is Peter Drew – a 29-year-old Australian urban artist currently working towards a Masters degree at Glasgow School of Art. In his spare time he's transforming the city landscape in his own special way. And without anyone's permission.
Drew first came to Glasgow two years ago, on his honeymoon. "We were looking for some spots to come and study for a while and we really just fell in love with the place," he says.
Now he and his wife Julie are studying at GSA and Drew is continuing the street art he started back in his home city of Adelaide. "I'd done a project around the idea of outlaws that was based on archival photos of criminals in Adelaide in the 1920s, and I stuck them up all round town as a play on criminality because what I was doing was vaguely illegal also."
The project began after he was arrested for another street art project. It's an occupational hazard, presumably. "What I do is something I consider to be for the public good, but it's misunderstood by the civic authorities." he admits.
Now that he is doing a similar project in Glasgow, postering the city with images of friends, family and people he's met here, isn't he putting himself in the frame by revealing his identity to The Herald?
"In my experience it works out if you have the best intentions with what you're doing. I'm getting out there by going out and doing it anyway. And that's part of the excitement. To see how people react to it."
So far he's put up 10 sets of images. "More than half of them have been taken down already but that's part of it.
"I wouldn't actually want them to stay there forever. It's kind of nice for them to disappear and for people to miss them ... hopefully.
"I really like the idea of art you can share and to my mind that's the solution to a lot of the problems we have with art.
"As soon as something can be bought and sold it becomes a commodity. Contemporary art definitely loses a lot when the only way normal human beings can relate to it is seeing that some billionaire paid some ridiculous amount of money for it. That's what I like about street art as a movement. It creates work that everyone can share and feel that they own."