In reply to Si dH:
I've got a pair which you can try on if you want, to get an idea. I think mine are size small, but I wouldn't swear by it, and they fit very snugly.
I've not used them in anger yet, bought them over Easter. I bought them a fairly tight fit, cos I got used to my old gloves which I could tie laces etc with, and missed that when I started using the lobster mitts. I'm planning to use them for leading, and then I've got that big pair of lobster mitts for seconding and belaying, where the dexterity isn't as much of a worry.
Let me know if I need to bring them anywhere ofr you,
AJM in the lab