Hi Phil,
Damn good to hear from you! Actually my family has some Scottish blood in our ancestors, my sister had a DNA test done, we're a bit of a Scandinavian, Scottish/Irish, German mix. In other words we're a Western European mish-mash. The official name of that tartan is Stewart Hunting Ancient, I contacted a tartan shop that does flat caps and they knew exactly what I was looking for. The only question was how I wanted the pattern oriented on the cap. Jackie has worn several caps of that tartan and they're all differently oriented.
I opted for the blue strip down the center for two reasons, Jackie's teammate, pupil, and dear friend Francois Cevert had light blue stripes on his helmet, and Jackie's rival, and good friend (and my boyhood hero) Ronnie Peterson wore a blue helmet. I like to think Sir Jackie would approve of the reasons for my decision.
Cheers,
Fax