Solitary Bee

I saw this land on the wall beside our local railway station. Maybe it was nesting in a hole in that wall but it was sufficiently exhausted to allow me to poke my camera within a few centimetres of it to get this macro.

It is a solitary bee of some kind but a quick search through Google's images failed to throw up a good match and deterred me with the information that there are over 200 species of solitary bee in the UK!