As I recall, the yellow bike in this photo matches one in white that appeared with a similar question in our Forum archives in the past.
At that time, I believe Dave Whittle mentioned it was not a Thorn per se, but a bike made in Japan and marketed by SJS Cycles as a winter bike for a short period of time.
Best,
Dan.
It is a frame bought in by St. John St cycles and sold cheaply. It is certainly not a Thorn .
Our posts crossed. Yes.