Sorry folks, I solved this thanks to the great site posted by lynn - Desdemona's website.
The solution was to drop the items - immediately the Quest Log had the quest, and I could give the items to the Rebel Elder.
However, I repeat that this sort of thing detracts enormously from one's enjoyment of the game. I'm now paranoid about the wretched Quest Log, I keep checking and re-checking it anxiously. Horrible.
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