CC,
1. So how would we have been able to reach an en-route controller with the wrong squawk in the first place? Surely this is picked up by the tower/approach controller?
Sorry, I was only talking about transfer from tower to departure sector.
2. Are you saying if we have the wrong squawk set then it automatically displays an arbitrary callsign?
In the UK it usually does, because we approach code saturation often, so chances are that any random code will be assigned to another flight, so you show their callsign.
3. How many a/c is an en-route (area) controller allowed to control at any one time? And what is the norm on a typical day? Anywhere near this limit?
I'll leave that to those who work en-route.
4. If the answer to the question above is something like 13 or 14 then when you ask someone to SQ-I how many others are likely to SQ-I at the same time, in the same place to cause you confusion?
Again, it's not the fact that others might sq. ident at the same time, the identification of the aircraft is achieved when the callsign of that flight is observed identing after that flight has acknowledged the request.