I was thinking about this some more last night--like, in my office, I definitely don't feel above average in size, and walking around the city I really don't, but the sizing does bother me! So, I can do the UK 12 on the bottom and sometimes, sometime a UK10 on the top (depends on the cut, really), and when I shop for that, then I start to feel like I'm on the bigger side given what sizes are available in the stores. I'm not the thinnest girl in the world (on the short and curvy side, so if anything fits my hips, it's way loose in the waist and about 90 inches too long) but in NYC I did find more clothing in my size available.
I know this is off-topic for a second, but is tailoring very expensive here? My brother and my sister in law sent me a coat for my birthday, but I think it's a smidge too large, and I can't return it, obviously, and to send it back and forth for them to return it seems a bit silly, too.