I would like to remind everyone here that there is no such thing as an "illegal" strike. Everyone who works (with some exceptions) has the right to withdraw their labour in a time of dispute. The fact that a union hasn't organised it just makes it unofficial. There are some legal implications, admittedly, but
I'm given to understand that this walk-out was fairly unanimous (and from what other posters have said- well supported from other parts of BA) and consequently could be defined as spontaneous action because of a failure of the dispute process.
As for militancy...I would suggest that the numbers involved indicates some deep-set and long-term grievances, that haven't been dealt with or even acknowledged by the management.
As I believe I said before...these are ordinary people like you and me...to make them take this action suggests that circumstances have become intolerable.
Final three greens...I'm afraid that the unpleasant minority is no longer insignificant, I speak from experience. (so much so, that it is a now H&S requirement for companies to have protocols and procedures in place to protect those staff dealing with the public from abuse and violence) but we're getting off the thread here.
I hope that BA management see this as a wake up call...there is a lesson to be learnt here...the only way to ensure successful change is to engage in proper two-way dialogue with everyone concerned...other airlines have successfully changed to meet new circumstances, by doing just that.
IMHO the most successful companies are the ones that realise their staff are a resource not just assets.