Expressflight
LCY I guess is a good benchmark as to the field performance of what can land at Southend today (in particular on RWY 06) - the only difference is that they're all doing a 5 degree steep approach which I assume actually reduces the landing roll by some margin. If you were comming in at 3 degrees (i.e. normal approach), I suspect a lot of the LCY aircraft types may have to have lower payloads to get into just 1285m at Southend? Not sure about that one?
Although the extra 200m runway may have the support in principle by the local authorities (and the majority of the local community for that matter), when it comes to the crunch and the're an election in the wind, politics can play all sorts of tricks when the lobbyists get their knives into local councils - it's not 'in the bag' until the JCBs are on site! Planning concent is everything - unless I've read that wrong and the planning concent is indeed in place already for the 200m - if so forget all the above and I'll shut-up!