Mr reid, thank you for incidentally answering something that I have often wondered about t and that was did BEA and BOAC reverse the odd even flight numbers .
As to the main question it is really difficult because obviously as a passenger London to Hong Kong was a long haul flight but you could fly there ona medium haul aircraft on one of the many complicated west east routes from Europe that stopped every five or six hours. I also think 747 -100s could fly to NBO but not fly back due to altitude there and SAA used to fly a 747 Clasic non stop to Joburg on Mondays-a very very long haul but again couldnt operate the reverse direction.
For what it is wrth my personal view was that short haul was LHR to Helsinki Mocow and Cyprus. Anything beyond that but less than westbound transatlantic was medium haul and JFK Tehran Bombay etc were all long haul. No such thing as ultra long haul back then as although some flights were scheduled LHR-LAX lots of times they made tech stops until the DC10-30 came along .
of course as far as LHR was concerned if it was BEA it ws short haul if it was the other lot it was long hail and if it was Cyprus or Rome it could be both.
Also how would one class the great BOAC route from Tokyo to Jo burg via Hong Kong . Colombo Seychelles Mauritius