Having a railway station on site will only enhance Southend's ability to attract new business. The Parkway station completed in the late 1990's at Luton, now forms an integral part of the airports infrastructure, albeit a bus ride away.
With HM Govt banging on about the use of public transport, having a station at the airport would be a significant milestone. Add to the equation a quality hotel, then Southend looks well placed to handle expansion.
Southampton does quite nicely with a short runway, an airport I am sure Southend would wish to emulate?