I am sure that the catchment area for SEN, be it 2 million or 5 million, will not prove a problem to the success of routes from SEN.
Also, it has never been suggested that 750,000 pax are expected to use the airport by 2009 and the planning application gives a figure of 500,000 for the capacity of the extended terminal. In any event annual capacity in itself is not a useful number as it must take into account seasonal peak demands or diversion capacity which may be very demanding if only for short periods of time.
It is often assumed that routes from a 'new' airport must poach existing traffic from similar routes already established at relatively nearby airports (although to say that SEN is 30/40 minutes from STN by road is stretching it a bit). This is not the case and the phenominal success of the LCCs is based upon the fact that an entirely new market is opened up. People who would not normally have flown to a given destination have been found to do so once services are available from what they regard as their local airport.
As a small example my family in the Southend area have generated 12 passenger movements on the SEN-JER route this summer. All of these were additional holidays, over and above their normal 'main' holiday, and they would not have flown to Jersey had the SEN route not existed. The same will be repeated on any other new routes opened up.
The catchment area around SEN also has no relevance to inbound flights from European or UK cities opened up by airlines seeking a near-London arrival airport.
One has only to look at the success of routes from NWI - is it some 14 destinations served from there now by Flybe?
The Southend/Rayleigh/Basildon area is twice as populated as the Norwich conurbation and the population of Essex is twice that of Norfolk, so a similar route network from SEN should be sustainable.
My fear had always been that RAL would not modernise the existing terminal until some new routes were inaugurated (the 'chicken and egg' situation), but that now seems to be going ahead and must be a good sign.