CS
"the sixties, with the introduction of Doppler "navigation", BOAC decided to sack all its specialist navs; to be replaced by bright young third-pilots from Hamble, who would spend much of their time practising astro for their Nav Licences. Maybe Rainboe can confirm? Some excellent redundant BOAC navigators found their way to BUA and Caledonian. BUA (later Caledonian-BUA/BCAL) realised that Doppler is useless over smooth desert or smooth water, so we copilots were full-time P2s."
That might have been your perception but it is incorrect.
Africa was a mandatory Nav Area, so the third pilot was in the RHS co-piloting whilst the Flight Nav qualified P2 was navigating (using all resources he had - including Astro and the wx radar to locate "Nasser's Corner"). In those days, pre INS, to be a P2 in BOAC you had to hold a Flight Nav Licence as well as your ATPL. The Third Pilot had a frozen ATPL with a full P2 rating on the aircraft. The only place a "bright young third-pilot from Hamble, would spend much of their time practising astro for their Nav Licences." would be a non Nav Area.