I've found Ron Hill clothing to be quite random fitting. I generally wear a size 10. My tracksters (size 12), just about fit me. A long-sleeved top (size 10) is also almost too small. However, I just got a vest (size 12), and it looks suitable for maternity wear on me! I went running in it yesterday, and it was way too loose.
I've found other brands to be just as random. But then again, I find that getting regular clothing to fit my shape is just as hit and miss. With regular clothing, I find that there is a fashionable female shape (not hips, large breasts), which is certainly not like me, so this is why I have fitting problems. But only god knows what sort of shape running clothes are patterned on!
Can anyone shed light in this?