THE school dinner is the working mother's best friend. In the mornings, rounding the children up with bags, books and sports kit can be quite a challenge, without having to equip them with lunch boxes. And isn't there enough to do in the evenings without devising appetising sandwiches and mini-snacks for the children to take the next day?

But school dinners are on the way out. The School Meals Campaign recently expressed concern that many newly opted-out schools are no longer providing lunch, in order to put more funds into educational resources. This has been going on for some time, and not just in the opted-out sector. By the end of 1992, local authorities from Dorset to Lincolnshire had dispensed with school meals for all, or part, of their educational establishments.

So what? some may mutter, remembering mounds of greyish potato and unspeakable custard. School dinners may be reviled on many counts - stodgy, dull, unappetising - but they are convenient. Until 1980, they also had to meet minimum national nutritional standards, but since then LEAs have been free to determine nutritional quality. To be fair, some have succeeded in improving the quality.

As well as pressing for the reintroduction of national nutritional guidelines, the School Meals Campaign also asks that meals be made available to all children who want them. And here we have it. Not all children do. Setting aside special needs, the packed-lunch vogue has more to do with parents giving in to faddiness, fashion and peer-group pressure than common sense. Expense does not necessarily come into it, when the price of a bag of crisps and a canned drink - almost obligatory items in the lunch box - is taken into consideration.

Packed-lunch boxes are also so naff. They are a nuisance to carry, a problem to store and ecologically unsound: all that foil, plastic and non-recyclable containers.

And what do shops provide in response to the demand for children's food? Over-packaged, expensive little salad pots or yoghurty things. 'Oh, but they can eat healthily. They can have a chicken leg, a ham roll or some taramasalata,' say those considering switching to packed lunches. Imagine a chicken leg or a ham roll that has been sweating away in its cling film in a warm classroom for three hours.

Furthermore, children's social skills and manners are not improved by wolfing sandwiches from a plastic box in some grim 'area' designated for packed lunchers. Quite different from sitting down together to a reasonably nutritious hot meal on a plate with a knife and fork.

There is more to food than eating, as the old saying goes, and this is nowhere more apparent than in a primary school. Some children start school hardly knowing one end of a fork from the other. Learning the basics of eating, without turning the stomachs of one's companions, is a useful skill. I'm not suggesting that teachers should be responsible for instruction in table manners as well as their other tasks, but many schools managed, until the recent decline in hot dinners, with a system of older pupils as monitors.

There is a powerful incentive for children to behave in the way they see older children behaving. Opening a sandwich box teaches nothing, except possibly how to go on a picnic or visit McDonald's; although as secondary schools' meals services - and possibly the secondary schools themselves - have begun to resemble burger bars, it could be argued that this is entirely appropriate. More's the pity. Or rather, less is the pity. It is not uncommon to find the 'informal' style lunch - launched with a reasonably nutritious selection - quickly degenerating into a flabby burger or pizza every day. It is sometimes abandoned altogether.

And what do you put in a lunch box for a teenager? Teenagers tend not to have lunch boxes. The boys buy a bag of chips, the girls eat a diet yoghurt. The popularity of the 'continental day' seems to be gaining pace. Children who arrive at school without breakfast and eat next to nothing for lunch will be too weak to concentrate on lessons after two o'clock. Sending them home early is doing them a kindness. Not their mothers, of course.

It's no use saying that French mothers manage; those who work full time often leave diabolically early in the morning, rush home in their extended lunch break to provide a meal for their returning children, go back to work, then home again to cook supper.

The abandonment of the school dinner is a nuisance all round. As a parent with children at primary and secondary schools, I come into contact with parents, teachers and helpers who all share this sentiment. Primary teachers have to deal with children who turn up with no sandwiches, those who just bring sweets, with leaking cartons, spilled drinks and stacks of plastic boxes.

Secondary schools have to work out whether to let 11-year-olds out at lunchtime and often succumb to installing food dispensing machines on school premises. The only people who benefit from the demise of school dinners are snack manufacturers and fast-food merchants. School cooks and dinner ladies lose their jobs, teachers their tempers.

The quickest way to abolish the school lunch service is to persuade parents that they don't want it. If more parents supported the midday meal, instead of joining the packed- lunch brigade, schools would find it harder to do away with it - on whatever grounds.