When on Hastings doing the NBS course I was supposed to attack a reservoir dam up in North Yorkshire. I misidentified it and "bombed" one in the next valley, which had a very similar response on the H2S (well anyone can make a mistake).
The RBSU duly scored my bomb and sent an error of nine miles (we were hoping for about 400 yards). Messed up my bombing figures bigtime and probably clinched my posting to Victor tankers instead of Vulcans, so it wasn't all bad!