If we're talking miniature railways, does anybody else remember the Southsea Miniature Railway? The station was on Clarence Esplanade, about where the Blue Reef Aquarium is today, and the line ran alongside the sea wall out to a balloon loop which was taken in an anticlockwise direction, from memory. Arriving back at the station, the loco was uncoupled, drew forward onto a turntable and after turning ran round the train. Apart from that, all I can remember was that it was green and it wasn't steam!
The last time I saw the line was in 1984, when it seemed to be in a derelict state. The balloon loop was much smaller than I remembered, but that was because I was much bigger by then!
Interestingly, the historical views on Google Earth go back to 1985 for this area, but sadly it's just fuzz and no detail can be seen.