Hi Lou,
I tried on a fair few including the new look one & found that I had to go up at least 3 dress sizes to comfortably fit my growing bust. Finally came across one in m&s limited collection that fits really well & is really warm.
The link is http://www.marksandspencer.com/gp/product/B002F7KU0Q/sr=1-1/qid=1255010442/ref=sr_1_1/278-0221908-0832205?ie=UTF8&node=&m=A2BO0OYVBKIQJM&keywords=&mnSBrand=core&size=9&rh=n%3A43063030%2Cn%3A161475031&page=1.
It's really cosy!
Good luck with the hunt!
Rosie 17 + 0 xx