I'm pretty sure that wasn't there earlier - this is my landing window so you walk past it all the time. A pigeon (I'm guessing) must have flown right into the window. I got a fright - but I can't imagine how the bird felt!
Recently I was working (I work from home) and I heard a really loud impact noise, like a football being kicked really really hard against something. At the moment my desk is in the attic, I looked at the cat, but he was asleep in the same room as me and hadn't even looked up at the noise. I set off down the house, wondering if I needed to shout at next door's kids for kicking the ball against something ... and then I saw this