A mid air collision at the Duxford air show last month between two P-51 Mustangs. Both landed ok, thankfully.
You can see it here about 10 min into the video.
Also, my flickr friend Roland got a great shot of the damaged Mustang Miss Helen. Roland has a fantastic collection of
aviation photos - worth checking out.
A similar accident occurred at Duxford in 2011. The Mustang pilot was able to bail out before the plane crashed.