I think we've got “half brioche” nailed, including the discovery of a name for it.
Jeanfromcornwall, do you mean that article about EZ in the Sunday Times magazine, long, long ago? How I wish I'd kept it! It was the first time I had heard of her. I sent in a stamped, addressed envelope (that dates it a bit) and got back the mimeographed pattern for a double-breasted version of the Baby Surprise. I have knit it many times, and that tattered sheet has been annotated with the pregnancy-code-name of many a dear person.
I cut out and kept the pictures of the Baby and the Adult Surprise, but alas! alas! not the article. Why on earth?
As for half-brioche, I prefer the version I typed out here on Wednesday or Thursday, where alternate rows are plain knit or plain purl. The alternative, producing I think an identical result, is to do yarn-overs in the “off” rows. My way has k1b in the “on” rows instead, where the next stitch on the needle, the one you might have expected to knit if you hadn't been told to go below, settles down to serve as a yo.
I didn't get to Kathy's Knits yesterday, so no progress on the hat, but I have finished the v-neck ribbing on the vest except for binding off and ought to progress to an armhole today.
I won't forget to be poised at the keyboard when registration for the EYF begins today.