Perhaps it indicates that they are now getting their design right for a lot of younger women - on average (and I say, very much on average, knowing there are plenty of very slim older women) we get a bit sturdier as we get older, so that might be why larger sizes have been available in greater numbers up until now, to appeal to their traditional slightly older demographic. I am well upholstered myself, and know that I have been able to find things I really like in M&S for the past few seasons. Maybe younger and slimmer women than me have found the same.