Standard TCX procedure to move the a/c around to suit the school holidays. Has become more noticeable since local authorities have begun to stagger the school hols. "Glasgow Airlift" has been going on for years due to the big difference in Scottish term dates. There was a big (up to 2 week) split between England and Wales, so the tour operator has captialised on it. Just hope that every hol is sold at a profit.