Litebulbs, I agree that BA would have to say something like 'we consider this strike to be unprotected, thus withdrawal of labour will constitute a breach of contract, and therefore will instigate dismissal proceedings against strikers on that basis' Ie, the law will decide at a later date. BASSA/Unite would tell CC they were protected, and the CC caught in the middle would have to decide who to believe (staff travel back in 5 minutes?)
That way, strikers will not get a P45 in the post, but would return to work and have a long drawn out wait, and BA would have plenty of time to recruit to fill the finite number of vacancies created. Presumably there would need to be a test case or an action against Unite first.
But, this is all hypothetical. I don't think BA will go that route. At some point they will have to build bridges with CC as a whole, and 'forcing' people to strike break under threat of dismissal will be too far.
However, BA may take legal action against Unite, if they think they have a case. Is there not a court case still pending re the original strike? BA don't seem to have any qualms about taking on Unite as a whole.