Where the blue-tit wasn't

Busy day, working at home on more exam questions with additional LaTeX wrangling. When I went through to hang up a load of washing on the airer I could hear some lovely bird song coming from somewhere in the trees outside, so I got the camera and spent some minutes craning my neck in all directions but was unable to locate the source.

Still, I thought, even though they weren't the singers there were three or four blue-tits in a nearby tree who I thought would look quite pretty for a blip. I waited till one sat almost at the very top of the tree, focussed on him and.....click. He was gone. So I have to give you the vacant tree top.