The clean-up engenders tremendous enthusiasm: teams from schools, local authorities, companies and other sources compete, and all ranks not only enjoy themselves but gain the impression they are doing good.
So they are. Yet surely there is something wrong in the fact that the drive against rubbish can produce such a colossal harvest. The total of 10,000 tons represents a phenomenal number of individual items, most of them very light: how many million sweet-wrappers, tissues, aluminium drink-cans, plastic bottles and burger boxes?
No doubt the litter problem is worst in towns. But casually rejected garbage is even more offensive in the countryside, which should be a green environment.
Are we a nation of sluts? I often think so when I ride around our lanes on a bicycle, whose modest pace gives an all-too-detailed view of the immediate surroundings. There appear to be two kinds of litter vandal: those who deliberately drive out to fly-tip large objects - cookers, refrigerators, TV sets, mattresses - and those who casually throw things out of car windows.
I hate both classes: the first because they are too idle and/or stupid to go to the council tip - an admirably-run establishment that accepts any domestic reject and directs it towards recycling; and the second because they have no thought as to the problems their slovenly behaviour may create.
How many motorists realise that bottles are killers? In a recent survey a naturalist found 77 mammals trapped in bottles around a single lay-by on the A5. Another survey discovered 2,000 mice, voles and shrews - many dead from hunger and thirst - in 900 bottles thrown into hedges and bushes. Plastic bags can be just as deadly if eaten by sheep or deer.
Living on a lane that runs nowhere, I conduct periodic purges of my own. The most recent yielded 24 alien objects, including seven bottles: three glass, four plastic. Local people would never throw out such junk - and nor, I believe, would walkers. It must all have come from passing cars.
I believe there is something about cars that undermines normal standards of behaviour. People would not dream of dumping rubbish on their own territory. Yet once in a car, they are in a separate little world. They do not seem to appreciate that every wood, field and hedge belongs to somebody, just as their gardens belong to them. The apparent lack of any owner acts as a licence to jettison.
The question is: how to change habits? Leaving or depositing litter is already a criminal offence subject to a maximum fine of pounds 2,500 - but it is difficult to catch defaulters in the act. The long-term answer is surely better education, both at school and at home. As Ginette Williamson, co- ordinator of the national clean-up campaign, remarks, litter should be on people's minds not for 10 days a year, but for 365.
My only criticism of her splendid effort is that it comes a week too late. Already the wild garlic, grass, nettles and other plants along our lane are high enough to hide unpleasant secrets.
Walking out the other evening, I picked up some chips of rock which had fallen into the road and tossed them on to the bank. Clink! Glass. A freshly- landed bottle? No - a one-pint beer glass, not cracked or chipped, perfectly usable. God knows who threw it there, or why - but I'll bet my boots it came from a pub and sailed out of a car window.
If you wish to join the clean-up, the hot line number is 0990 885577.