Many years ago whilst flying from Blackbushe I turned downwind and called "G-ABCD downwind for runway 07"
Immediately after I heard "G-ABCE downwind for runway 25!"
Bottom clinching moment as I saw this other aircraft in the distance heading towards me at circuit height! Mental process kicks in - "Am I in the right, or is he??"
As it happened he quickly realised that he was in the wrong and turned away, having been confused about the runway change that had occurred whilst he had been out of the circuit!
Lesson learnt by both parties, I hope. Check runway in use, and check again!!