Scottish winter belays are no place to select the wrong choice of insulated jacket to use. Any winter belay is normally going to take at least an hour while the leader does battle and during that time you will have probably been exposed to rain, sleet, snow and spindrift to name a few.
Keeping warm is the name of the game in situations such as these and Marmot's Ellsworth jacket offers an excellent balance of warmth verses weight. Slip the Ellsworth on as soon as you hit the belay, synch in the draw cords and prepare for belay duty.
Read more at http://www.ukclimbing.com/gear/news.php?id=2158