Mid to late 1970's BA routed to HKG with Middle East stops in Dubai, Abu Dhabi or Bahrain at different times. India stops were usually Mumbai (then Bombay) or Delhi. I can recall wandering around a mixture of these airports in the middle of the night during a technical stop as a child in the late 70's and early 80's on route to/from HKG

Routing across China (and Soviet Union controlled airspace) was very limited, plus 1975 and 1976 flights were having to do a dog leg around Vietnam ( requiring a stop in Bangkok in addition). Not sure when the closure of Vietnam airspace came to an end so could have continued into 1977.

The first non stop HKG to LHR flights didn't start until 1983 with Cathay Pacific and initially that was only one direct service per week.