Never come across that Hong Kong routing before - very exotic, and also quite clever, since it links northern England to the Persian Gulf, Thailand and China with a single flight.
The Munich stop must have been intensely irritating for passengers, but all BOAC's eastbound flights used to make stops in Europe in the 60s and 70s, and this Munich stopover is clearly a hangover from those days. Presumably they could pick up and drop off pax wherever they stopped, but if you were flying from London to Melbourne or Tokyo or somewhere, after flying for two hours, landing, dicking around with fuel and baggage etc, you'd be four hours into a very long journey...and we're still only in Germany! I like takeoffs and landings but if I'm going to Oz, I at least like to get a few thousand miles into the journey before the first stop. And really, two is enough.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz