I think P51 is correct. In days of old co-pilots arrived on jets either from military flying or by coming up through the QFI/Air Taxi/Commuter airline route and so arrived 'in the seat' with a basic survival instinct and ability. The 'straight into a jet and you will learn those two important aspects on line (possibly at your expense)' scenario is relatively new. In an airline like BA it is probably quite safe - I flew with many such F/Os and apart from a complete lack of experience they were competent and as said have gone on to make fine Captains. It should, of course, be remembered that not only were they selected as above average candidates but also had a good and thorough training system to aid them on their way (and, of course,
outstanding line captains for their formative years..........................
) - not always the case.