"Uncle-C" wrote
Now that we have had 2-3 days of frost in the S.East of England I want
to ask if there is a chance my dahlia tubers will survive if I do not
lift them for overwintering..

Norfolk here. My plants have managed one revival - I chanced it last year
after finding out my neighbours never lift their dahlias and theirs have
survived many years. I think it depends how free draining your soil is,
and you can always cover the spot with extra mulch if we get really low
temperatures.

--
Sue