TUI Holidays have now quite a lot of 3rd party airlines flying for them during the past few summers instead of using in-house TUI Airways, with departures mainly out of the Outstations -
EXT NWI CWL SOU SEN BOH BRS ABZ DUB to name a few.
Volotea, Freebird, Alba Star, Sunwing, Flybe, Norwegian, ASL - Not just ACMI charters to cover the MAX debacle, but many regular charter series for the past few summers...Turkey, Spain and the Canaries being the majority of flights but not exclusively so.