Sorry to crash - I am a Mum Uniform jeans and t-shirt / sweatshirt person, but I saw a few of these today in 
Sainsburys and thought they looked like a good idea.
Mainly because the cardigan part is also the back of the "dress", so no bulk. Also, no worries about the sun shining through and exposing your Granny Pants thong to the world in the summer.
I remember reading about haute couture and the tricks they use such as having no fabric bar sheer silk under a "belted" waist and thought this was clever along similar lines.
Or are they terribly wrong on all counts? If not, what are they actually called and where can I get some nicer ones? 