I'm slim, a big 8 / small 10. I love Tu at Sainsburys just for the convenience of grabbing stuff with my food shop, and my favourite work shoes are from there and have lasted FOREVER.
Previously I've been anything up to a size 14, but I am reliably always a size less in sainsburys AT LEAST.
In the past this has been ace, and I've swanned around in my size 10 dress feeling smug. But now it's a PITA.
I'm not a rare size or shape, but the size 8s are HUGE and in hindsight even when I was swishing around in my small size dress I don't think the shape was great either.
However this pales in comparison with H&M who have taken the total opposite strategy and make shorts my DDs Barbie can't fit into.