Flying into Farnborough on display days sadly is not an option, but flying into Blackbushe, about three miles up the road, certainly is.  As with Old Warden, you'll have to book in advance, and on the day, pay handsomely for the privilege.  You will be given specific arrival and departure slots, and you will have to make your own arrangements for the journey to Farnborough itself.  Unfortunately Big Bad Charlie Bravos put paid to plans to take BG up there this year, resulting in Plan 'B' being put into operation, i.e. hop on a train...