Mark Hewitt wrote:
... Only slight problem was they showed hearing the cattle onto the Skye ferry supposedly to go from Skye to the mainland, but the footage they showed showed them putting them onto the boat on the mainland side! I can understand why they did that as there's a lot more space but a glaring error from anyone who's been there

With the way that TV works, it would not surprise me if they put the cattle on the ferry several times and just those were the best shots so they used them.
When was the road along the old A87 line built? Just reading Telford's report of 1803 and that seemed to be to open up the fisheries with no mention of cattle. An earlier road ran to Loch Hourn, I have a copy of the notice asking for tenders for its construction.
The Sixth Report of the Commissioners for Roads and Bridges in the Highlands says the "Glengary road" should have been completed in 1812 but "the extra work performed by the contractor, overbalanced the savings and deficiencies by L.260".
A sudden flood overthrew the bridge over the river Quoich in 1811 - attributable to a fault abutment so remedied at the expense of the contractor.
From Inch Laggan to Loch Oich, about ten miles of the east end of the road, it will be much frequented by droves of black cattle which will travel from Skye and part of Ross-shire, by the future Glenshiel road, turning off to the southward at Rhiebuie.