Orkney Image Library

Having posted a brooch myself on this site without much luck, I racked my brains, and the slightly larger internet, for a clue to yours Doug - but to no avail. The central badge resembles the left-hand side of the official Orkney Coat of Arms, but whether the green diamond with white bulges means anything I have no idea. I think it's probably just a mount for the county badge, and would have been the same for all counties. The point of a brooch like this would seem to be to indicate its wearer's county of origin amongst a group of people from other (probably only Scottish) counties. Who would need to be identified in this way? Guides at a Scottish jamboree, or whatever they have? (It's nothing like their badge). SWRI teams at a nation-wide rhubarb-jamboree? (Ditto.)
Possibly the Heraldry Society of Scotland would be able to help. I take it there are no clues on the back of the brooch.

Thankyou Ian.
I have searched about quite a bit and like you; to no avail.
Will try the H S of S.
Dropped a clanger with the family name, Should read Firth.

If you come up with anything Doug, please do post it.

I don't know anything about the history of the badge, but the underlying design is intended to represent Arms for the Earldom of Orkney and these have appeared in a number of Coats of Arms for Earls of Orkney. Indeed, the present Earl of Caithness has them as the principal Arms in the 1st quarter of his coat of arms with the Arms for the Earldom of Caithness in the 4th quarter, the 2nd and 3rd quarters, having a gold background with a red lion rampant, being for Nithsdale, with the Sinclair engrailed cross counterchanged Argent (white) and Sable black overall dividing the four quarters.

As Ian Hourston says, the left hand side (dexter in heraldry) of the Orkney Islands Council shield of Arms have the same underlying design but without the 'double tressure flory counterflory' design of the Earldom of Orkney Arms and which appears on the brooch as a single line with stars attached. The right hand side (sinister) of the Orkney Islands Council shield has reference to the Arms of Norway.

I should point out that when it comes to things to do with heraldry, after a quick search in reference works, the place to go is the Court of the Lord Lyon who are responsible for all things heraldic in Scotland. The Court even has quite friendly staff who only show their teeth when threatened!