thanks for your very informative and helpful response. As a speaker of english since birth (or thereabouts) one rarely thinks about the contradictions and many double meanings in the language. I am now paying serious attention to learning Gaelic at the age of 70, so the different meanings of words and expressions jump out at me, whereas I probably would not even think about similar issues in English. It does strike me too that Gaelic has preserved many old words which have gone out of use in English - the most recent one I noticed was truinnsear for plate = trencher: the wooden board medieval people ate off.
I have seen "saor alba" in the past, and I noticed its usage in the course for "cheap". Thank you for the explanation. Peter
Saor This usually means 'cheap' in the context of prices, using saor an-asgaidh 'cheap in a gift' to clarify when you mean 'free', and 'free' elsewhere.
I think the political use may have been prompted by use in Ireland in the early 20th century, such as
Saor Éire 1931, later revived
I cannot find any references to Saor Alba that suggest any significant age so I think it must be quite recent.
Of course you might think that there was no justification for an Irish origin since Free Scotland is simply an expression of what the SNP wants. The problem is that it does not translate as Saor Alba, but rather Alba Shaor (and similar in Irish). Saor is not an adjective here, but an imperative. It is a command to make Scotland free (which also translates into English as Free Scotland ). This is the usage that I think is more idiomatic and needs an identified origin.