Advice required on keeping spuds alive for the rest of the year!

My Autumn potatoes have been in a couple of months and have around
12-18" of growth, though they're already banked up so not that much is
above the surface.

However, they've now been hit by frost twice. They had almost
recovered but was cold again last night.

I plan to put some fleece round them, but are there any other tips you
can suggest? Have I in fact left it too late to get any decent spuds,
as they look much smaller than the plants my neighbours had in the
Spring?

Colin
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