That’s all incredibly helpful. Thanks everyone. The good news is that after 3 hours chasing at the airport office they have found our missing luggage to check back in tonight. Perseverance paid off as initially they said they had no idea.

Luckily we are both lawyers so will have a good look at the really helpful instructions in the other thread and read the case referenced. Just to clarify if we did go down this route the suggestion is that we deal with the downgrade with BA direct and then the delay separately potentially relying on the case above? I am trying to persuade my husband it’s worth a crack at least given there is 5 of us….