A family friend used to have a farm in that general vicinity and I spent many a happy teenage summer there during the 70s.
That must have been a steel sign though as I remember many (most?) of the classic cast iron signposts were broken off by, allegedly, the welsh nationalists of the day. Curiously, our friends were from farming stock in Shropshire but never had any problems with the locals. Perhaps it was just the holidaymakers they disliked at the time.
I cant tell you what the sign was made of as it was up at 1st floor height on the gable end of an old stone cottage in the middle of the village. Needless to say the cottages gable end was covered in concrete which was then made to look like painted stone. The paintwork on the sign did look a bit too new for the sign to be original.