Red mason bee a possibility? seems to say they live in colonies.
I put a post on national beekeeper's website. So perhaps this will inspire me to get a hive and get a wriggle on as I have been intending to give it a go for years. I have missed our local beginners course but a friend said I could go to a society meet to try it out and see if the bees liked me...apparently not everyone liked!...can't believe that
I'll take the camera this afternoon.