@peterbrown From memory I did some reading around this topic a while back. I think the settlement after interaction with the outside world just became unviable.

@bibliolater well that was certainly the narrative. But they had had continuing contact with the Isle of Harris for centuries. If there was a poor harvest on Harris, they would send the young men over to St Kilda for the winter where there was a guaranteed food supply.
The government refused to organise a Postal Service or even a ferry but the straw that broke their back was infant mortality. A particularly clarty nurse was sent out and they kept losing babies so their spirit was broken.



@bibliolater however little more than a decade later the government suddenly found they were able to install a permanent military presence on the island and had no trouble in supporting it. (they still do)

If only they had been as supportive to the resident population as they were to the military.