No doubt you have all seen this super weight - I was surprised to see it described as a triple overlay when clearly it is only a double overlay.
I didn't recognise the design so delved through the Perthshire book - no sign off it ! I then happened on the Perthshire section in Ann Metcalfes PW's of the 19th and 20th century and amazingly and to the word is the E-bay description !!!!! except that it is describing the triple overlay 1977c - which the weight on E-bay clearly is not !!!! I cannot detect any sign of the edition scratch signed on the base of the E-bay weight which is the normal practice so suspect it is a one off trial pice or frigger.
I have e-mailed the seller asking for clarification and will post the response.