Well, it was a long post DFC, but I don't think that it proved your point. Enroute ATC units are under no obligation to do anything with flightplans they might receive (however filed) from aircraft that will primarily be operating outside controlled airspace and may simply call on the offchance for a transit.
Finally if one reads the AIP one will see that flights to/from Fairoaks and Blackbushe are required to address te plan to Farnborough........good idea because the first unit we will call will be Farnborough and often we will have a squalk from them prior to departure..........using Vintage ATCOs rules, farnborough should bin the plan and we should pass full details on departure!
It would be a mistake to confuse the general situation with a local arrangement between certain airfields in close proximity with one another.
2D