Not so I think
Stansted never did have many charter aircraft allocated there, did they ever have more than 5 even when Air UK Leisure were based there.
And places like Liverpool, Edinburgh and Belfast seem to have many more charters than say 10 years ago. And look at the "new"charter operators springing up like Astraeus and Flyjet, or the increase in size of Excel.
There appears to be no real low cost attack yet on Greece, Turkey, The Canaries, Madeira, Sanford .... the opportunities go on.