Glyntaff (1st station)
I know this one is going to be controversial, but it is shown very clearly on the 1901 1:2500 OS Map, with platforms each side of the line and a small building on each platform. It was just east of the bridge over the River Taff. The same map shows "Halt" at the Glyntaff Road overbridge, a few hundred metres further east. By 1919 the platforms had disappeared and been replaced by sidings. Anyway, one for the ever-growing list of sites worth further investigation.