In reply to Offwidth:
I know of three recorded cases of finger de-gloving across europe, non from the UK and all outdoor.However, there maybe the "odd" other that I am not aware of(my disclaimer) These were climbers wearing rings and forcing their fingers into small sharp pockets. One climber leading, the other two were bouldering.
Also, one recorded case of traumatic amputation of the thumb, by a climber who grabbed the rope falling off and it formed a lasso around his thumb and it cinched down as his fall was arrested, squeezing tight and "tearing" his thumb off. Again outdoors, and not in the UK.
Statistically, I would class these as "freak" accidents, which are not significant in real terms of climbing injuries (unless you are the climber involved) as so would, apart from using some common sense regarding ring wearing, I would be more concerned about knot tying, and poor belaying (indoors), and setting up good belays and helmet wearing (outdoors).
Without getting into the debate about "competency"
Hope that helps to put it into perspective
Cheers
Nick B