Does Size Matter?

Last Friday morning a (male) colleague asked my friend what dress size she wears. Yes this was a random question but he had prefaced the question by asking her if he could ask a personal question and saying that of course she was free not to answer. I asked him why he wanted to know, as this might make my friend more inclined to give an answer, and he said that someone he knew had told him that they wore a certain size and he thought they looked about the same height and build as my friend so he wanted to make a comparison.

I immediately leapt to the defence of women in general and pointed out that someone can be the same weight and height as someone else, yet they might still be different dress sizes. And my friend pointed out that it depends what shop you are in as to what size you would wear (the day I wrote this I had on a size M top, with a size S top over it, and an XS sweater over that. Two of those items were from the same shop. Yes, H&M, I am looking at you and your ridiculously erratic sizing!). Equally, two people of very different height and weight can wear the same size clothing. My friend is probably 6 inches shorter than me and a different build, and yet we wear the same size clothes.

What is your experience of this? Do you find inconsistency in sizing across different (or even the same) brands? Does it bother you when you have to wear a different size to your usual one? Do you share a dress size with someone who looks has a completely different body shape to you?