Hmmm ... I posted a reply to this thread earlier, but it seems to have mysteriously vanished into the ether? Let's try again.
I suggested that larger regional airports such as MAN and BHX would be wise to get their own lobbying organised early to avoid the possibility of ending up in the higher tax-band alongside other operations deemed to be well-established and successful.
I also highlighted the dilemma faced in categorising certain London Airports LTN, SEN, STN etc. which would resent being penalised alongside LHR and LGW in the higher APD bracket. LCY would also make for a very interesting case-study as a smaller operation, but one defined by high-yield business traffic drawn from the City of London.
This could become complicated!