BA already operates with this in place for one route, namely INV-LHR, which is APD free. This route is already a good option to consider for WTP to CE UuA fares, and anyone who lives in ABZ with a 2-4-1 should also price it up via INV. There is a long list of other places without APD available as codeshares from BA. I once flew from Campbeltown to GLA and on to somewhere like TLV and I noticed the fare was lower than starting from LHR.