I forgot to mention that there is actually a mason bee near the left hand bottom corner busy at a nest in the previous pic.

The owner told me that this bee house is up now for 3 years and the first year there was only 12 holes filled but since then its been full every year. They have made another 2 bee houses since then (again with 6 x 20 holes drilled )and they are as full as this one !

Some very happy bees in that garden.

Thanks very much for the pics...I have been trying to research this and had a time trying to find an actual picture of one in the works. I am going to try and make some of these. It seems to be such a simple thing to do for wildlife...thanks.