The red sashing fabric is a much lighter weight fabric than the white squares, and has split open in several places. I found an absolutely perfect match for the slightly faded turkey red color at Reproduction Fabrics (www.reproductionfabrics.com). It was so perfect, that I bought a bunch of it. And I mean a bunch. With any luck, I've got enough to repair any such quilt for years and years to come.
Here's the "before" picture, in which you can see Nana the dog, Tiger Lily, and Smee. (My daughter was Smee in a dance version of Peter Pan when she was about 12, and I've had a fondness for ol' Smee ever since.)