in 1968 when British Eagle were using their Britannia for the immigration charters to Australia,the flying time was about 36 hours with a total journey time of about 40 hours
The routing was London-Kuwait-Ceylon-Singapore- Darwin- Sydney.
With the VC-10 in the early 1970s it was much more popular to go via the Pacific route
which took about 30 hours flying with a total journey time of about 35 hours. The routing was London-New York-Los Angeles-Honolulu- Fiji- Sydney