Telegraph insulator

I recognised this piece of pottery on a Westray beach instantly. It’s that bit attached to a telegraph pole which insulates it. All I did was photograph it. Little did I know that there are collectors of telegraph insulators. There’s even a Telegraph Pole Appreciation Society. There are hundreds of antique telegraph pole insulators for sale on Ebay. There are people who could tell me what year this was produced, what year it was taken out of service, what replaced it and which firm manufactured it.

I left it there for someone else.