Lou Shannon - crewing levels on longhaul flights never change. Even if First is completely empty on both outbound and inbound flights there will be same amount of crew.
Previously there were 15 to 16 crew on 747 with less than 300 pax - a couple of years ago when 747 carried almost 400 pax the number of crew was the same!
If BA removed another 50 seats from 747 - UNITE would still be insisting that the crewing levels should be the same. Go figure.