Great point, nailed it. In truth, Gatwick is not the realistic alternative to LHR. It could and should have been once upon a time but we are where we are now. Some fair points about the subsidy but the reality is that it's an oddity for the likes of LHR and LGW to be seen purely as private businesses. The privatised rail and energy firms by necessity get a host of public subsidy, mainly because there's a good arguement they should be publically owned. Both LHR and LGW are major parts of UK PLC infrastructure and will require public subsidy on some level on some points. The genuine argument for both airports is "How much?" TFL (a state body) have vastly inflated LHR costs in their world with the aim of getting a whole load of new money. Of course this is all politics.....