Gatwick is a different market to Heathrow. In the case of long haul most, if not all, of Gatwick BA flights are to leisure destinations such as Caribbean, Mexico, Indian Ocean using the B777-200 whereas Heathrow concentrates more on the premium business routes using A380, B787, B747, B777-300 and 200 with different cabin seating layout. The short haul destinations from Gatwick are for similar reasons. Also Heathrow's runway capacity is full for virtually the whole flying day hence using Gatwick runway slots for other destinations not served from Heathrow or to add more frequency on existing destinations served from Heathrow. Gatwick's runway capacity is also constrained but they are permitted more night movements than Heathrow which gives some more flexibility and improved aircraft utilisation than perhaps some Heathrow short haul based aircraft. BA occasionally transfer Gatwick short haul destinations to Heathrow and vice-versa to make best use of the slots to make the best yield.