I have seen truck gardeners do this around where I live. The idea is to get the early jump on vegetable seed germination. I guess it can be done as soon as the possibility of snow has past.

I have a huge blue tarpaulin, big enough to cover my 3 raised beds.
Would it have a similar ( but lesser due to the colour) effect as black polythene ?

Often used on allotments to get some seeds in a few weeks earlier. Not sure blue would have the same effect, Hank.

i cover my little plot as soon as its empty...not only does it warm the soil but it so easy to dig when its uncovered.

only if a bin bag inadvertently blows on it and no one notices it . I don't on the flower beds as there are lots of perennials in it that wouldn't like the dark! the slugs would love it though.
a good technique for 'catching' new Zealand flatworms however.

I was questioning whether February was the right time. Heavy soils need hard frost to break them up and we haven't had that yet in (most of) the UK. The theory also needs some sunlight and I wouldn't have thought that there was enough energy yet to be effective.
So his black plastic might well be a marginally useful weed suppressant at the moment but I'm not so sure about it warming the soil just yet.

I only cover empty beds Urbanite

There are many ideas for getting 'an early start' for vegetable seeds and I have tried some. In my experience you might be able to sow a month earlier than normal but the resultant crop is only ready about a week earlier than normal. Given all the extra effort needed to sow earlier, and then protect the seedlings, is it worth it. I don't think so.

I live in a heavy soil (clay loam) area and a lot of local farmers use the biodegradable resin 'plastic' on their crops. There are 2 - a black one that is a mulch that you cover and weigh down with some soil and cut into for crops and a clear one that acts like a greenhouse over the crops. It must do something or they would not be investing in it.

My farmers do the same Botanic but when you are racing to the markets with an early crop it can make all the difference.thats why we make such effort with our tomatoes. But my veggie patch is covered as it suppresses the winter weeds and makes it easier to plant come the spring.

Not much use listening to the Archers for gardening tips any more. The new editor used to write for EastEnders, which explains a lot.

Thanks Stera - that could explain all the bed-hopping (of the non-plant variety)

Apparently the BBC has been inundated with complaints but the writer is unrepentant and sure she knows best. I think lots of folk will be stopping listening after many addicted years, and I'll be one of them.