Peter, the backplate of Nathan’s lock is clearly marked YALE Made in ENGLAND.
Yale updated our British dead locking 82s every time they changed their standard night latches, so there are quite a few variations of them- I can think of four going back to the 1970s off the top of my head. I don’t know which one you were thinking of when you tried to upload a photo.
Nathan, is the case die-cast? The backplate is typical of UK latches from the early 1980s, although I haven’t seen one with that distinctive radiused bolt profile before.