Thanks Kidbeey and Wild Bill.
Kidbeey, of the 5 long strands you start with, 2 are dark and 2 are light. The 5th strand is half dark half light that is glued together and hidden in the point of the plait when you start. That way you get the same colour on the both edges of the hatband. I like that better than if one edge is dark and one is light, although that still looks good.
I'm not sure if I've ever tried two tone herringbone with uneven strands. I'll have to give it a try sometime. My 'give it a try sometime' list sure is getting long...
Pete