Sunny 16 used to work fine for me here in Devon, as long as there weren't many clouds. If it was Sunny with clouds, I went for Sunny 11, normally relying on exposure latitude. I don't need to do that anymore now though, seeing as I got a Sekonic L-8 meter. It's extremely reliable, and dead accurate. Highly recommeded for fast, easy, and accurate metering. There's also a free PDF Manual knocking about in the depths of the internet.