pipistrelle:
"...that they should have priority over foreigners"
This is an extremely dangerous attitude to take. I would suggest that there are far more British pilots flying for overseas airlines than vice versa (SQ, CX and EK just for example).
I have personally flown for airlines in the USA, the Far East, the Pacific and am currently flying for a European airline. I think British pilots have traditionally gone wherever the work is.
We have about 15 different nationalities in my present company and we ALL get on very well with each other.
I do however agree that the practice of flagging-in should be stopped.