The oracle has spoken.
I’m not signing up an account just to reply, so feel free to pass this on…
As others have said, it can’t be Isle of Arran. Too early – they didn’t build their distillery until 1994, and didn’t distil until June 1995.
So the labelling is important. If it says “bottled by” IoA, then it’s a cask they bought and resold to keep revenue flowing.
If it genuinely says “distilled by”, it’s a fake or a cruel joke. Or a truly bad labelling mistake.
Either way, there’s probably no way of knowing what it is without going back to IoA themselves (who may have records), or to the company who paid for it (who sound totally trustworthy! Honest!)
A picture of the label may help, but other than confirming it’s not IoA I can’t do much – sorry.
Isle of Arran do produce some small scale blends – so they may have had casks.
That doesn’t help identify it, but does show it may be genuinely a cask of whisky. However, it may have been teaspooned, so has no provenance.