In reply to steveshaking:
Yes, that was an abortive attempt by two of us. As I said earlier, there's only one way to find out..
We backed off half-way up as the turf was not fully frozen to the rock. The route was doable ... but the turf would have ended up at the bottom. As not to strip the route we left it for better conditions.
The problem is that the turf was not wet enough when it froze ... quite surprising when you think of all the rain which came before, although the quarry is well drained and dries in the SW winds.
Anyway, my advice would be to leave the routes until the conditions improve (snow,bit of thaw, freeze would do it).