Have lived in present terraced house in town centre with only a concrete back yard for 24 years. Today, doing BGBW, saw song thrush and 2 pied wagtails in garden for very first time. Did they know the BGBW was on?
Same thing happened to me a few years ago. I was doing my one hour and in that time I had a Jay and a Green Woodpecker turn up amongst the regular visitors. Couldn't believe it!