until I ring British Airways later (when they decide to open), can anyone explain to me why the cost of a 1 hour connecting flight from manchester to heathrow is almost half the price of an 11 hour flight to san diego?
No but I did find when pricing a trip to the US that it was cheaper to fly Manchester than Heathrow, even though the Manchester routing flew down to Heathrow and linked up with the same plane! Have you tried booking straight through from Manchester, or is the other leg already booked?