raveng, for many in BA it is not as simple as leaving if you don't like it. Pilots are tied in by the seniority systems and to leave would mean the likelihood of starting at the bottom with someone else.
For Engineers I guess they are unlikely to be able to get a similar position for the same money, and often the ones who have been there many years have a pension at BA which if they went elsewhere they won't be able to get the same standard of benefit.