A bit batty today (possibly)

Another predominantly grey and gloomy day (if I'm sounding obsessed with the weather by now it's probably because I'm the daughter of a meteorologist!) so I didn't bother taking my camera with me when I walked the dogs. Typically, I then noticed these, which I snapped with my phone. I think they might be bat boxes, but I'm no expert.

Does anyone know? Bats? Birds? Insects? Something else?