The road in Cheshire that I referred to above is different ... To keep a stretch of road permanently lethally slippery just round a tight bend and not even bother to put up warning signs is grossly negligent. If the farmer's tractor were leaking oil all over the road and he left it there for years at a time, then he would rightly be done for it. What's the difference?
I'm certainly very sorry to hear of any cyclists being injured at any time, but if the hazard is there as much as it seems to be, the organisers may want to re-visit their risk assessment.