In reply to Jkewley:
Not British winter but I have a pair that I used in the Alps last summer.
Overall, they are great - massively easier to hike in and climb rock in. They are terrifying on hard ice as too much flex to front point in and although the soles are stiff enough to edge on snow, once you've got crampons on the lack of ankle support makes traversing hard going. Not that either of those will be of too much concern for grade I.
However, they are basically glorified trainers; amazingly light but clearly not going to last all that long or especially warm. Unless you're really after the lightest possible boot I'd probably go for a pair of 'normal' B1s instead.