At the time the Wizz "red eyes" established at LTN were the only method of creating extra slot capacity at a constrained airport.
With Wizz anxious & willing to build LGW that creativeness will no longer be needed at LTN probably.
Wizz have also stated recently too that LTN has infrastructure & planning constraints..."so we want to grow elsewhere in London".
That reference in the context was almost certainly LGW...however.