I share to a limited degree
@CV12Hornet's concern about the LEANDERs, but a decision to not go ahead with RAF Mount Pleasant seems very unlikely to me even in this timeline.
Even if the formal capabilities of the airfield might not be fully used, and the threat from Argentina very limited for the time being, it displayed a formal commitment to the future defense of the islands to the Falklanders - and in a very
tangible, concrete way. Also, it meant spending a fair bit of coin locally, too.
Otherwise, a solid and fairly plausible update, Flash. You put some thought and research into it. Well done.