I'm with RTS on this one. It's not just the waterproof on the outside that matters, you need enough layers of good clothing inside; although trying to enforce base layers may be a step too far for kit-checkers!

I have been wearing Helly Hansen long-sleeved top and leggings on most of my runs in the recent cold weather, on hills that are nowhere above 250m. But then, I do tend to be rather conservative in my choice of clothing (I once wore a woollen sweater in a fell race!); and I would rather be uncomfortably hot on the initial climb than having to faff around putting extra clothing on when I reach the exposed moorland.