Hi Margaret,
I can explain a little about this...
For many of our Christmas holidays there isn't the option to fly to the destination on the days we fly from London with the main group. We have also found where the option does exist, the supplements tend to be much higher. In the past, we have offered regional departures on our festive programme, but found that there wasn't the demand for it as customers sought to connect through London at a lower price.
It is worth mentioning that whilst we don't actively advertise regional departures on our Christmas departures, one of our advisors would be happy to quote for the holiday with a regional departure if there is a flight available.
I hope this information helps.
Kindest regards,
Julia