Are you sure it's a set Linda? Does it have the matching label? The colour seems slightly different to the red on the sweater, more orange-red than blue-red.
Yes, I've seen lots of '60s sets too but not '40s sets like yours. It's common for people to match items though, and store them together. I've just done a house clearance where there were many like this, but they weren't made to be together. As you say, when you see it, you'll know. Photos don't give the full story.
If you have not already seen it, you may find this Catalina label resource page helpful: http://vintagefashionguild.org/label-resource/catalina/ That size 14 tag looks newer than 1940s to me, but again, in person you probably will be able to gauge better. A size 14 in 1940s could have measured about 28" but bust and waist sizes were more commonly used than "size numbers" like 12 & 14 -- the size numbers were just beginning to be developed in the 1940s.
Linda, waist sizes are not stretched - the stretch is to provide extra comfort. If you measure it unstretched too, and also the hips, you'll get a better idea. Length also helps. If the two pieces have been worn together, it's probably a similar size to the cardigan.
That really is a stunning sweater, Linda! You're collection is pretty wonderful! I could not help but giggle when I read your typo "Lactose track suit"
