Hasn't the 777 fleet at LGW broadly replaced the old DC-10 fleet which was the old BCal long-haul operation? In the 1990s Gatwick extended its main runway to just under 11,000ft so that the DC-10s and (back then) 747s could operate to South America with full payload but since then a lot of the major destinations have been moved back to Heathrow. The long-haul destinations now are primarily leisure focussed and include places like Orlando, Bermuda and several points in the Carribbean but as WHBM points out there is a degree of its own catchment which has allowed some services to the busiest destinations like New York to re-start.