BOAC yes, exactly right, I simplified it, for which I make no apology.
alibaba, if you check the actual distances involved, most of the alternates you mention are significantly further away than LPL when you factor in the actual tracks you will have to fly to get there. Add the fact that, unless you declare an emergency, diverting aircraft do not get priority at the alternate over that alternate airfield's own inbound traffic.
Then there is the commercial factor. Operators often have lists of preferred alternates, where ground handling, engineering, etc are available more easily. Of the list you mention, BLK would be a last resort (1869m, sure it's doable but why go looking for trouble?), and
AFAIK BA only have a presence at LBA and BHX. Again, LBA has its own issues, so I suspect BHX would be the next option- far enough away that the decision to divert would have to be taken a lot earlier than when diverting to LPL.
All of which is a very long way of saying, I agree with you, good airmanship to prevent unpleasant surprises later.