Many moons ago, when I was a sweet young thing, I used to sew a size 12 straight out of the envelope. Ah, those were the days. I was a runner then, and my body shape was different (I also suspect the Big 4, which is what I sewed exclusively back then, has also changed their fit models, but I have no way of checking). Then I did a number on my knees and I started cycling instead; not competitively, but I was on the bike a fair bit for long distances. Enter a truck/bike MVA and some damage to my neck so the mountain bike was not so comfortable anymore. I still ride a bike, but mostly commuter cycling.
However shortly before the the accident I started rowing and my shape has changed again. I am broader thru' the shoulders and more muscular across the back. Good-bye straight size anything; I am now a vexing mish-mash of sizes, as you will soon see.
Behold Renfrew I. The picture is less than optimal, as are my construction techniques. I don't remember what size I cut out and I am waaaaay to lazy to go all the way downstairs to the sewing room to look. In this size it is too narrow in the shoulders and too small in the bust but fits well in the waist. I find the length a little long for my taste and the neck doesn't sit quite right, but I think that may be due to said construction techniques.
Renfrew II: cut two sizes larger in the shoulders and bust but the same size in the waist. Those areas fit well, but the neck gaps even more. That is not constuction problems but my own structural quirks. I like the length on this one better and I left off the bottom band.
Wish me success!