Prior to ANY FTLs in Feb '56 we flew. as a single crew (Captain, F/O, F/E and R/O + Cabin crew) on a U.K. Government charter for the routine replacement of personnel between Salisbury (SR), Singapore and Lusaka (NR). Accommodation had been arranged by the Government for the passengers in Aden and Colombo ( each way).
We stayed on the Government's schedule for the 16 day trip. We flew for 119.10hours in 15 sectors but there could have been a further 3+ hours if we had needed to refuel at Karachi on our return flight. as well as outbound.
And that was a Government charter. LEGAL ? Yes, by the standards then current. SAFE (potentially) ? Not to today's standards, i'm sure.
I do not know just how much thought had been given. Many sectors were on routes with which we were unfamiliar.
The Captain was killed in the Blackbushe accident, some months later.