Now that my home airport has been mentioned:
75,000 inhabitants in Ciudad Real proper. Catchment area: 216,000 (30 min), 394,000 (60 min, 3,951,000 if rail station is built), 1,629,000 (120 min, 5,178,000 if rail station is built). Travel time between CQM and Madrid-Atocha would be similar to that between SEN and London-Liverpool Street.
1,260,000 in Barcelona proper. Catchment area: 4,200,000 (30 min), 6,000,000 (60 min), 7,300,000 (120 min).
183,000 in Southend-on-Sea. Catchment area: 8,200,000 according to marketing team.
One of the reasons I moved to Southend Airport for work was that it reminded me in some way of my local airport. SEN is for me an example of how good planning and a convenient train station can attract new airlines and passengers. Under new management, CQM is also improving but with a totally different business model (aircraft parking and, in a few months time, maintenance and scrapping). Until a railway station is built in the mentioned high-speed line, Ciudad Real cannot realistically attract any passenger service except for regional/low-cost traffic (to Barcelona and Balearics/Canaries in Spain and to Romania). The managing team knows this and they want to consolidate as a maintenance hub before trying any other options. The previous team (up to 2012) also knew it, but when Madrid "took" all the low-cost companies that were meant to operate in Ciudad Real (Ryanair, Wizz, Blue Air, bmibaby,...), they rushed everything with the results we all know.
Back on topic, it's difficult forecast what the future will bring to Southend, but in my personal opinion it is a great airport to fly from or work at, and the airport will maybe struggle for a couple of years, but there will always be new opportunities that, if management takes advantage of them, will get everything back on track.