For anyone who has been watching the box for the last couple of hours ... I think we had a visitor ... bird at the north end of the box was definitely Smiley, he had a wander into the nestbox and was doing some scraping and I could see his leg band. However, the bird that was on the south end, I'm pretty sure he (by size) had a silver band on his left leg. I suspect it is one of ours, most projects only put coloured bands on the left leg, we have done both. This isn't the first time a second bird has turned up at the nestbox since Princess and Smiley lost their eggs, however, I couldn't be positive (until now) that it wasn't Princess as I had to use the box-ledge cam which meant I could only see both birds from a great distance (in relative terms) and couldn't gauge size accurately enough to be sure. It would explain Smiley's reaction - couldn't be sure at the time as it was a very quick visit, but it makes sense now ...