I surfed the web trying to find the yarn, Bergereine and could only find one place to get it in North America, Club Direct Laine in Québec. I promptly ordered their catalog (~ 10 USD) and received it last Friday.
It's a beautiful catalog with color cards of all the yarns. Here's the page that shows Bergereine.
So now that I've seen BdF yarn what do I think of it? While all the yarn is eye-appealing, almost all of it contains lots of polymide and/or acrylic. My current project with Debbie Bliss Cashmerino (which has 33% microfiber) will probably be the last time I knit with microfiber. Isn't microfiber just a trendy name for acrylic? I find that wool is much more forgiving and comfortable to wear.
Bergereine is the only pure natural fiber (50% wool / 50% cotton) yarn in the catalog so I'll probably go ahead and make this sweater with it. Marie is currently working on a sweater made with Bergereine and finds it easy to work with.