On an approach into EGCC (Manchester) in poor visability, I was allocated runway 24L, this runway has no ILS so I requested 24R, my instructions were to approach 24L then sidestep to 24R, this was fine until I approached minimums to find that ATC had allowed an aircraft to line up on the runway right in front of me, this initiated a rapid avoidence and go around (not funny). It appears that once a runway has been initially allocated ATC continue to believe that that is the runway you will land on, even after clearing you to land on the parallel runway. This can also happen at LEMD (Madrid) on runway 36L.
Keep your eyes open.:@