Those with long memories will remember Luton when it had a selection of light aircraft based at the airport by the flying club and when Fields of Heathrow handled business jets.
The signs are there that Luton has passed its peak and will be on a slow decline just like the airports light aircraft were until one day they were no more.
Basically Luton is now a no go area for biz jets from midnight until 07:00 and even after that time I doubt they would find many slots until after the morning rush.