[twic]

Aha! I was wondering what the "granitic" aspect was, thank you. These are basically cement tiles, but with the backing cement made with granite sand. These were the final (?) evolution of a line which started with medieval encaustic tiles:

https://www.theantiquefloorcompany.com/short-history-encaust...

As for finding some, there is unfortunately no mention of Threlkeld in the Database of UK Architectural Ceramics Locations:

https://tilesoc.org.uk/tacsdb4/tacsdb__LOCATIONS_list.php

[justincormack]

I am sure there are lots around in the UK though. Tiles are everywhere.