Jakob Jakobsen, An Etymological Dictionary of the Norn Language in Shetland…
“ But the coast regions of Scotland, lying right opposite to the Hebrides, had already a greatly preponderant Celtic-speaking population, and there was thus no bulwark that could defend the Norn of the Hebrides against the steadily continued pressure of the Celtic of West Scotland, which at last overwhelmed it. The Hebrides, also, lay much farther away from Norway than Orkney and Shetland, and were separated from Norway at an earlier date than these latter Island-groups, that is, immediately after King Håkon Håkonsson’s ill-starred expedition to the West of Scotland. ”
