I just checked... and CAA says 'nothing has changed'.

CAA spokesman: "UK aviation security regulations do not require a passenger’s identity to be checked for security purposes prior to boarding a domestic flight, in the same way when travelling within the mainland on a train or bus. Any further requirement on behalf of the carrier to provide identification may be a condition of travel by the carrier itself."

I suppose it remains possible that something has changed but it's nothing to do with the CAA; I haven't asked BA as I fear that asking them will result in the (much appreciated by me) current policy being reviewed but I'm happy to if the issue continues.