Yeah I think you might be right Paul - which would probably mean this is the female, so a bit odd perhaps that she is having a look inside? Lots of bluetit and great tit activity in general around the garden now - the new pond has been a revelation in terms of attracting birds to the garden. I am trying to compile a few pics of different species that I take from my office desk at the moment. So much more activity than last year - here's a few pics, I think the one of the bluetit might be our usual suspect himself: