Well, at my heaviest I was still in denial and squeezing myself into extremely old and stretchy and very generously cut size 18 jeans from Dorothy Perkins tall range. But I had 50 inch hips, 38 inch waist, and 50 inch bust, so I must have been at least a true size 22. I never bought anything over a size 16, though, except that one pair of jeans!! Just goes to show how you can delude yourself with the vanity sizing that a lot of the shops go in for - and I usually wore super-stretchy stuff.
I didn't weigh myself while I was losing the bulk of the weight, only weighed myself when I was just under 10 stone. By then I was a comfy size 12. At 9 stone 5lbs I was into a size 10, and at 8 stone 12lbs, I hit the 8s.
I think the weight gaps between sizes get smaller as you go down the sizes, if that makes sense. If there's less of you I guess it takes less weight loss to trim off a size.
But these are all Dorothy Perkins/M&S/Next sizes for the most part. They're very generous. Still haven't mustered the courage to go into Topshop and see what I really am!