It still stands that if you buy something you're not happy with (whether fit, size or you just decide it's not "you") you can return it for a refund or an exchange. The difference is that from now on, you will need to pay for the postage of the replacement item.
So... let's say you buy dress X in a size S, and decide you'd rather have the M. You'll need to pay for postage costs for me sending the size M. This brings the Pin-Up Parade returns policy into line with most other online retailers. Since the pound fell against the dollar, it's been difficult keeping prices low, so the money saved in this way will be passed on to keep any price rises low.
The only time this won't apply with exchanges is if there's a manufacturing flaw with the item or I've made a mistake with your order! In which case, I'll also cover your cost of returning the item to me.