Again: Any economic benefit is going to be confined to work caused by the airport..
There IMO is no other sound reason why an airport should be the reason for a large increase in house prices..Also smaller airports tend to be more seasonable that the larger airports, just can't see SEN generating a 15% rise in the Southend housing market.
It has been mentioned that Southend as a resort has improved (see earlier in the thread), that is more likely to drive house prices higher, IMO.