If it doesn't look like anything the UK used, it's possible this was designed for Labor Services or some other quasi military organization working on behalf of occupying forces. In fact, I'm now pretty certain of that as I'm remembering that the US sector's stuff was made with US military tags even though it was produced in Germany for use by German citizens (in the employment of the US military).
If that's true, what you have is one of those things which is super rare, but only of interest/value to a very small number of people who aren't willing to spend a lot of money. I know because I had a few US sector pieces and sold them in Germany for not that much money. Very niche stuff.