I'm speaking as someone who lives in central London.
I'm glad you've clarified that Michael - I was wondering how you got to Heathrow from Swansea for £2
As Seat62K says it's all dependent on where you live and where you want to fly to. I live within an hour of MAN, LPL, EMA and BHX and there are enough (short-haul) options there for me to not have to consider flying with BA or, indeed, out of a London airport.