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Stornoway Castle (audio)
This nice two part reel is a good example of what is often known as an A modal tune, when the melody moves between the chords of A and G.
Although the key is A major (which normally uses a G sharp note) these types of tunes use a G natural note. They are usually bagpipe tunes, as Scottish bagpipes are not able to play the note G sharp.
You can find this sheet music in any of these products: