I bought the cream fleece welly socks in Large (6-8 UK). I am a size 7 and these were huge, I could have easily fit into the next size down. They are also quite chunky and my legs wouldn't fit into the Hunter wellies with them on. So unfortunately I had to return these socks.
If your calves are like mine and quite snug in the Hunter wellies already, then I wouldn't recommend this product.