That's a great story of how you wound up with the Mamod roller. Nice work! (Becoming a "roller guy" now?)
I have a special fondness for the Mamod vehicles. At just about the same time that your roller was new, I purchased the Mamod tractor version of that roller from (wait for it...) F.A.O. Schwartz! It was a Christmas gift for my little brother. I was trying to get him interested in my hobby, but it never "took". He acted grateful, but I eventually wound up with custody of the little steam tractor. I don't know whatever happened to it -- When my parents split up, a lot of things went in different directions, and I don't remember last time I saw it.
Anyway, seeing your little roller running brings back some nice memories!
Paula