ATnotts
You are, of course, correct about it being the Tour Operators who decide where and who flies the routes, but often it is one and the same thing, with the airline being owned by the operator i.e Thomson...Britannia/Thomsonfly.
I'm not sure where Excel fits into this pattern as they seem to choose some of their own longhaul flights and maybe sell blocks of seats to the operators. Someone might have more information on this.