I dealt with insulators in a previous life, mostly towards the higher voltage end of things - Bullers became part of Allied Insulators and we used a good bit of their output, as it was a little cheaper than the vastly better NGK stuff from Japan.
The old factory, with its very Stokey bottle kilns, would make a nice layout for somebody to have a go at.
https://www.alliedinsulators.com/company/history/
We did (inadvertently) blow up an insulator in a fairly dramatic manner in the mid 70s, whilst under test in Manchester, next to the Kellogg's factory - there was some damage to a lot of vehicles in their car park - and I've often wondered if we also contaminated their output, giving them the idea for Crunchy Nut Cornflakes, which were launched shortly after the event?