I'd like to pop my tuppence in as I'm not sure that this is a question of our interpretation of safety (that's the CAA's job, and the rules should be common for all businesses.)
AS a charter operator we get a huge amount of enquiries that ask for "any London airport", to this end I think if NHT was not an option the traffic would migrate to other London airports with Biggin getting a fair share (not so convinced that OXF's LDA makes it a particularly likely alternative for the AOC Ops, and of course it is almost in the Midlands). I think FAB and LCY may do well out of BQH and OXF's expenditure.
On the other hand, there is a question of what is right and correct. If the CAA allowed just one AOC holder to use unfactored landing and take-off distances then the rest of us would be up in arms - especially if that one operator was government funded by our taxes and publicised as non-profit making. I think it is totally appropriate that BQH and OXF have raised the question of fairness. It's simply a surprise to me that FAB and other Londonesque airports haven't put their hands in their pockets.
PB