In reply to JamesLamont:
I feel your pain! (often, and to the great amusement of some of my partners)
I wear mitts whenever it is feasible but the best warm glove I have found is the Outdoor Research Illuminator. For the dexterity and lack of bulkiness, the warmth is truly surprising. They are waterproof, so "should" be ok in Scottish winters - I have only used them in dry cold conditions, down to about -15C. (Norway, Canadian Rockies)
I have also taped a handwarmer sachet to the back of my hand which has worked excellently.