To generate traffic especially on the London route RE and GWY have to offer a definite advantage in time, convienience, service and reliability for their potential customers over SNN/NOC. Could this be achieved with the existing infrastructure? Possibly, if there are any small regional jets that can use GWY, but the economics may not fit. The 146/RJ7 was used a few years back to LCY and AMS, an excellent service but high cost aircraft.
The RE fares from GWY to LTN/SEN were already high relative to those from SNN/NOC, and if the breakdown was accurate some €50 was down to taxes and charges ex-GWY, which did not include the recently introduced €10 airport service charge, making RE's share of the total fare look very reasonable.
RE had to set up the SEN routes as part of the Stobart deal last year. The only way that a London service can be really attractive from GWY is to re-instate LTN direct at reasonable fare levels using a small regional jet able to use the existing runway at GWY.
Overheads at GWY could probably be reduced by using less ground staff more flexibly between the airline and the airport, but I am not sure what is allowed under current rules.