aaah the aber tank's 22:25 on the Loop at Shrewsbury to follow the last Down Aber and 04:00 off aber to get to bescot in time to do a light engine move to work the 1J20 on a saturday or worked down to cardif for the rest of the day on a weekday. was alway's a 37/4 when they came out i do remember seeing during the daylight it was with a 25 on after the one of the20's had failed (Before the 37/4's were released.)
The tanks were BP grey one's and one occasion the wheel centres were blue.
20's 37's and 47's were also used on the Shrewsbury Tank's which were also BP grey colour, but these never went to aberystwyth.