Winter spud anguish

hi all,
We've only had our plot for a couple of months and planted outside Maris Peer and Orla, 2nd week of August, as a 'winter crop' of spuds. They've taken off really well but, reading around the threads on Christmas spuds, it's becoming clear that I'd have done better to have stuck them in tubs in the greenhouse.
Is it worth me covering them in fleece, when it gets colder or do I just write them off as a bad job?

We're in Wiltshire, the plot is very free draining and is not dramatically exposed, but as we're out in the sticks somewhat, when the skies clear we're certainly a couple of degrees colder than the local towns.
Any help welcome.
cheers
Ian

Thanks - pretty much what I thought..
Cheers / fingers crossed for a late Indian sumer.
Ian

If you do use polythene, you do need to make sure you don't create ideal fungal conditions - cold, damp, little ventilation ...