This is second hand - or maybe third hand information - or even worse
Although the union has ruled out striking over Easter, members of its cabin crew branch, Bassa, remain determined to strike for at least 10 days. A poll on the Bassa website saw 70% of members back a strike lasting longer than 10 days.
reference:-
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I think I remember somewhere that the strike or strikes must be within 12 weeks of the start of the first strike.
No doubt someone can provide more reliable information than I have put in this post.