I think there are others around Borough High Street and Borough Market. It was one of the Notes and Queries on Robert Elms' show on BBC London 94.9 a few months ago, and I think they turned out to be an installation by a local artist.
I just discovered from her marriage banns that an ancestor lived in Roupell Street in 1860. One branch of my family moved from Devon to London for one generation before moving on to the Midlands, then the north-east, from where I hail. My ancestor appears to have not been living with her family in Roupell Street, so was probably a live-in domestic. She just misses the census, which was taken in April 1861.
Weirdly, I now live round the corner from there myself. So I brazenly knocked on the door of the house in question, and the chap who lived there could not have been friendlier.
Apparently a Jack Thurston has produced a short film about the street. I see from a Search that it was shown at the Tate Community Film Club last year. Anyone know where I can get a copy?