I'm not familiar with all of the details, but the cutting of charter flights was something to do with staffing levels, to handle that one charter flight per week I think the number of staff required was triple that of KLM/Eastern/Flybe, but, for whatever reason, the staffing levels required for the Thomson flight had to remain at that level all of the time.
There's people on here that should be able to explain it better and I think it may be in the master plan.