Perhaps Boris had better have a word in God's ear, because the site somewhere on the Maplin Sands is a bird migratory route and perhaps due to the changing weather systems a permanent bird nesting area. Can you imagine trying to get insurance cover for aircraft movements if the risk of bird ingestion were so high ?
The idea of placing the main airport away from the city is a sound one and will/would be made without thought to the business health of west London, but for the business health of London as a whole and the surrounding regions. As for whether this might happen in our lifetime is debatable. My guess is that they will build the 3rd runway and curse another section of this massive city to
near permanent noise pollution. I don't believe that the UK governments (whichever) are capable of making the huge infrastructure decisions that are apparent in many other countries in the world. We will see.
Regards
SHJ