Selkirk is my speciality with something like 100 weights (used to be more) by them, mostly by Peter Holmes.
Peter says they started making weights in October 1977 and I've never seen one. It's a holy grail for me, one of the missing links, so love to see pictures.
If you're thinking of selling it please do let me know, I would be very interested!
1978 was the first catalogue, I have a pdf of it somewhere....