None of these collective agreements is enforceable as between BA and the trade union
In a way this worries me, it is suggesting that in some cases BA could declare "open season" on the cabin crew. I don't think (hope) that they will, but it suggests that the union needs to go cap in hand to BA to "legalise" this situation.
They seem to be upset with the offer that the loss of ST will be over their heads for the future - this could be far more serious.
(though I can't prove it, was a figure of £4.8 million not mentioned as BA's costs at the time of the earlier case?)