Speaking as a regular consumer I think that ThomsonFly is a ridiculous name: it sounds more like an unpleasant disease that afflicts animals.
Why drop such a well-known and respected brand name as Britannia Airways? It is lunacy.
And names can make a difference. I was talking to someone the other day who was considering whether to fly from Bristol to Jersey with 'some new airline called Flyby or something.' In the end he had decided on BA (even that of couse is BACitiexpress from Bristol) because he didn't altogether trust new airlines 'in case they suddenly go bust'.
I explained to him that Flybe was the name and it was the latest name for an established airline previously called Jersey European (which he had heard of) and then British European.
Why, oh why, do marketing people want to stick their noses in to fix something that isn't broke?