Downy mildew attacking the onions on our site (West Sussex) and also on my Dad's in Surrey, manifested by leaves collapsing overnight, browny, distressed look - some people are leaving them in to see if they recover, others chopping the leaves off, others lifting them now. So far mine seem OK, though the shallots appear to have it, but they look ready to harvest anyway.
Should I just leave the onions (these are this seasons not over-wintering) and hope the weather picks up and reduces the risk of this mildew, or lift them anyway - they are a fairly respectable size (best looking onions I've ever grown actually - my two previous attempts have been major failures)