I'm not really that bothered (and I'd never heard of Manston, other than as a wartime RAF aerodrome, until it was mentioned on this thread). To be honest, though, I haven't seen any argument to convince me that splattering more Heathrow all over a heavily populated area is a good idea.
Fair enough, I guess - although there is a railway line practically at the end of the runway. And, is the journey to Heathrow that much fun these days?
Just out of interest, what would be wrong with developing Manston - and why, if properly developed, would no-one want to fly from there?
Must say the amount of destruction involved in expanding Heathrow does make it seem a controversial choice.