It is usually ThomsonFly but I cannot be certain.
I have just returned from a superb Caribbean cruise on Boudicca. We flew Thomsonfly and it was the best charter flight I have ever been on. Huge amount of legroom, good service and (for an airline) acceptable food. In fact, because the flights are chartered for the cruise, the atmosphere was great and we made many friends before actually embarking. Have a wonderful time.