Manstonman
The driving times I quoted are from Google Maps, so I assume they have made some effort to ensure that they are accurate.
SEN has a great deal to offer as a London area airport. The plans in place, which include a 250m runway extension and an on-site rail station, will enable SEN to realise its potential over the next three years.
While there is no guarantee that those plans will come to fruition, they certainly stand a good chance of doing so, as the new owners are likely to have the financial resources to make it happen.
As far as Biggin Hill is concerned, are you unaware of the high volume of bizjet traffic that it now handles? It's not just scheduled flights that a London area airport needs to attract to be a success.