Odd waistcoats are usually thought of for fall but they also add considerable versatility to light weight jackets that might otherwise be too cool-wearing for sunny days in the 60's F (17-18 degrees C). And on those days, patterned wool challis can be a good fabric choice.
Now challis cloth has been difficult to find since David Evans left the silk printing business, but worth while. A waistcoat from the stuff can add a medium weight touch of color to a country wardrobe.
As I related in my post on Winston Tailors this past winter I was delighted to flip through several bolts of challis when I was last in New York and I ordered a vest. I chose the maroon on turquoise paisley in the photo as I could not see myself wearing any of the canine or wild game prints that were the other offerings available. And though it looks like something a nineteenth century riverboat gambler might have worn, I think the finished product adds flavor to the soup.