I've also bought this one:
http://www.marksandspencer.com/gp/p...d=core&size=9&rh=n:43091030,p_10:Black&page=1
The fabric is a little bit clingier than some, because it's stretchy jersey material, and while it sounds as though that should be a total no-no, it's more flattering than it sounds, it kind of sits on your curves in the right places... so long as you wear a pair of magic pants underneath it.
It might seem a bit casual, but I've dressed it up to go out at night, with strappy shoes, and bold, colourful accessories in a burnt orange colour, and been complimented on my appearance in it.
The sweetheart-ish style neckline is also quite flattering, as with a pair of DDs I can't really go for those really really low cut V neck dresses that are in vogue at the moment (the kind you need a flatter chest and tit-tape for), as I need scaffolding to hold mine up, which rules out the very deep V. And it covers my rounded shoulders and the tops of my fat arms too.
I figure I'll dress it up and wear it out a few more times and then maybe tone down the shoes and accessories and get more wear out of it during the day time next spring. It's actually quite a bargain, too, at around £20. And they do it in red, although I didn't think that was as flattering as the classic black on me.