Wearing the kilt in Scotland

[Calgacus]

To my ears it sounds like 'islanders' too, and it would make sense as he apparently originates from the Isle of Skye, in the song. But either way I think it makes little difference, it's a comedy song written by a Glaswegian, so I'd put no weight whatsoever on its lyrical content.

There's no convention as such over the pronunciation of 'highland' or 'highlanders'. Both words are pronounced in one of two ways, the 'highland(ers)' variety being the standard English pronunciation, and the 'heiland(ers)' variety being the Scots pronunciation. The English pronunciation is probably the most common.

Yes, you are quite right, I think a discussion of historical dress in the highlands vs islands would make an interesting thread in its own right.