Reality here indicates with it now also being highlighted by current development that the site Luton Airport sits on is severely constrained in geographic/topographic/political/social & slot terms.
It appears LTN will max out shortly at the 18mppa limit albeit slightly higher with planning tweaks perhaps.
LTN is a victim of it`s own success in reaching max out much earlier than planned thanks largely to the WZZ group goldrush.
Further thought should be turning perhaps to route rationalization & airport usage with incumbents instead.
Are WZZ for example already recognizing facts with normal daytime slots (not red eyes) being acquired & actively sought now south of the river?