Open to become test case?
Balpa seem to have matter covered,so far at least,but this might also help.
Of course you could always try and possibly become a further test case but no doubt that would be costly and not worth it on an individual basis.
It would probably invite an HMRC enquiry into any tax return submitted incurring time and expense possibly outweighing the perceived benefit.
So suggest that you review in due course and ask Balpa again if they have made any more progress and then seek to backdate claim if relevant.
Do keep all paperwork just in case.