Many thanks for replies! I have just found what appears to be the identical badge on the North East Medals site, but fitted with 'normal' lugs. This gives me some confidence that it's an original badge but custom made for belt buckle with tombstone lugs - also found custom made for cap fitted with 'normal' lugs. I'm inclined to go with that, in which case, I will put it up for sale. Thanks again, Mike.
https://www.ebay.co.uk/itm/155101860...Bk9SR6Sp--uZYQ