Ostend-Southend used to be very popular in the past.
Don't understand why nobody tried to restart the line in the past.
Ryanair tried it at Stansted a few years ago but wanted a occapancy of 80%(had a average of 70%) with timings not so favourable and with a way too large aircraft.
A ATR600 or even Embraer 195 would be more suitable for a flight under one hour.