LCY does shut but one would have to check the detail. For example, is the restriction simply on operating passenger flights? Could BA therefore send up an empty plane? I don't know...
Also note that other E190's are being sent to other places to do similar things so how many would be left as backup?
Would it actually be the case that BA would put people on the next shuttle to LHR and then on from there to their destinations? How many of the destinations are now served from LHR? I'd guess all?