Hmm, all airlines do have delays, but the airport stats for Manchester and Gatwick suggest that they don't have delays in the same quantity as Flyjet:
July
Average delay on charter flights at Gatwick 24 minutes
Flyjet 44 minutes
Average delay on charter flights at Manchester 22 minutes
Flyjet 50 minutes
No airline is free from delays (particularly at this time of year) but it does seem as though some suffer a lot more than others....