Tartan authority - what can I wear?

[neloon]

Just for accuracy, "firth" is not Gaelic (it is from the root of fjord). The Gaelic for estuary would be "caol" (=narrow(s)) or, more usually, "linne" (=pool e.g.Linne Chluaidh =Firth of Clyde) or, quite often, just "loch".
Alan