Sam Rowley was so fascinated by these subterranean rodents, he spent a week down the tube trying to picture them.
And one night, he captured an image of two of them literally battling over a morsel of food dropped by a passenger.
That persistence to get the snap has won Sam the Wildlife Photographer of the Year LUMIX People's Choice award
See the other winners and read more https://www.bbc.co.uk/news/science-environment-51465064