Weirdly enough, I've heard stories about the high stret shops faffing with sizes - though I've heard about sizes being made bigger without the customers being told, as a way of making them feel good.

For example, a woman who is in reality a size eighteen trying on a pair of jeans marked as sixteens (which are actually bigger than normal sixteens) and thinking she's skinnier than she actually is. Weird stuff.

Though the whole sizes shrinking thing could be because skinny clothes are kind of in vogue right now, what with skinny jeans and fitted t-shirts and yadda yadda. Give me a pair of flared/boot-cut any day - I prefer the 60's/70's look :P