There were a couple like this near my old place in brum. One that appeared to be some kind of antique shop that had a sign up saying they opened by appointment only. My housemate did see it open once and had a look round. Another looked like a sort of gift/home accessories shop and was always locked up but still appeared to have stuff in it. I sort of assumed they were both doing most of their business online and just kept the shop as a place to store stuff, but surely a storage unit would have been cheaper.
I just looked up the 2nd one, it’s still there on google maps but says closed, and the web address on the sign isn’t recognised anymore. I moved away 10 years ago and the image on Streetview is from Aug 2020 so that’s a really long time for it to be sitting there unused.