FDF; I agree, all the evidence suggests that LHR is competing with AMS/CDG/FRA and not LGW...however, whether the politicians see that or not is quite something else!
Dave; is there any reason it was never an option? I've never read of the both scenario ever being proposed, but can't understand why? It would seem logical that HAL wouldn't oppose a second rwy at LGW given that, as long as they got their own third rwy, probably couldn't give a proverbial what anyone else does! Of course the flip side is also evident i.e. that MAG would certainly oppose LHR getting its third rwy, well aware that even if LGW got a second it couldn't compete...