Let's put this into perspective. The additional passengers at london's airports is not necessarily additional flights or routes, and is made up of many factors.
For example, If the average load factor on flights at Heathrow increases by just 2%, which with a buoyant economy and increases competition, is quite possible, then that translates to an additional 1.5 million passengers a year through Heathrow.
And this is wihout any additional flights.
Likewise if BA upgrade a load of 767 routes onto the 773 /747/ A380 you get bit increases in actual passengers, same with upscaling the A319 to the A320 and BA's seat intensification of the narrow body fleet.
With auch a large existing capacity base, these numbers translate into big passenger number increases
then add this effect up for Gatwick Luton and Stansted and you see that actually the efforts by Southend are in fact substantial and should be applauded, especially as Southend does not have much to start with so all growth in effect comes from the airports efforts in adding new routes and airlines etc.
I maintain they have done an excellent job, and continue to do so and don't deserve the constant management bashing they seem to get on this forum