whybyflier: I was equally sceptical about BA's long and seemingly irrelevant recruitment process but there must be something right about it. I say this because on a fleet of nearly 1000 pilots I can honestly say there has only been one or two times where I have wanted to get out of that jet and away from my colleague as fast as possible.
If it were me I would interview whilst showing candidates around the airline, have lunch together and then a sim test in the afternoon / evening. If that was all good then give the pilot a six month fixed term contract with the agreement that it will become permanent if x, y and z are met. In a previous airline the chief pilot was very honest. "We give out six month contracts and if after that time we like you or more importantly don't know your name then we give you a full time position"
The evidence I see would suggest that BA's system selects the correct people but it very very probably discards many very very capable pilots along the way.