Pilot DAR has hit upon a point that many in the GA community are unaware of, that is the costs and burdens of running an airfield. I was ignorant of it myself as a pilot until I actually started working at airports and seen for myself first-hand the challenges facing especially smaller airfields where income is minimal and costs are spiralling out of control due to aging infrastructure and increasing regulatory pressures from Europe.
Firstly, unlike other countries, we do not enjoy state subsidy of airfields, due to the traditionally anti-aviation attitude of the UK Govt. So airfields have to make their own income through charges.
Secondly, airfields have many things they are obliged to provide due to regulatory pressure - RFFS & ATC/FISO, with the associated staff & Firefighting/Tels equipment and maintenance obligations, Navaids, AGL etc. - note of which comes cheap. This all has to be paid for through customers.
Thirdly, most airfields date from WW2, with buildings still in use from that era - ATC Towers, Hangars, ancillary buildings etc. - all of which due to age are requiring increasing levels of maintenance and repair, with an associated increasing cost. Replacements are far too costly to consider. I have first-hand experience of this on a day-to-day basis. Cabling on airfields also dates from WW2 in many cases, causing issues with equipment. Runways, Taxiways and Aprons also require maintenance due to wear and tear, generally an expensive business.
As all these costs have to be met through customer charges, that means landing & parking fees, approach charges, hangarage etc. None of which are popular with us. But without that the airfield simply doesn't run. Smaller airports are stuck in the rut where costs are high but they cannot increase charges for the GA community too much as it will drive away people. It's a difficult business.
Bizjets are something of a cash cow as they tend to be operated by businesses and used by weatlthy individuals who will generally speaking willingly pay the fees asked by airfields. In contrast us SEP-drivers, many of us on an average income with kids to feed and a mortgage to pay, already are under pressure at £130+/hr for a hobby so additional charges on top of that make us baulk as we can't justify it, so we won't pay.
That said, I can't see the logic in Biggin's decision, which is saddening and maddening at the same time. Unless they feel that the light GA is constraining Bizjet capacity, its not justified IMO.