Lisa Markwell: The real taste test is getting our teenagers to eat at all

Ever since we witnessed the dispiriting sight of mothers feeding their children takeaway burgers through the fence on a Jamie Oliver show, school dinners have become political.

The seemingly unsolvable problem of getting healthy food into schoolchildren has seen many initiatives: the latest, the idea that canteens can offer discounted dinners for sibling groups or other targeted pupils, is heralded at a moment when it's furthest from parents' minds, it being the holidays. (For once, sandwich fillings are not a problem – my fridge alone could supply the entire Year 11 with turkey and ham wraps.)

But soon the battle starts again. Next week, when the weather is predicted to be chilly, most parents will want to know their child is eating something nourishing – whether it's a new boy who'd rather chase a ball round the playground than sit up with some wholesome soup, or a teenage girl with the twin obsessions of BBM and BMI (that's BlackBerry Messenger and Body Mass Index).

The idea of the admin involved in sibling discounts is mind-boggling. Surely they won't be expected to line up together to claim their bargain lunch? Any parent knows they generally repel each other for the secondary years.

There's no doubt that since Oliver's campaign there is more emphasis on healthy food – the main issue, according to my 15-year-old son, is that it's difficult to find anything worth eating once he's reached the front of the snaking queue; priority is given to the little ones.

Priority will be given to younger children in the new plan, too. I'm all for instilling healthy eating habits in 11-year-olds, but the teen years are when peer pressure and saving money for less, shall we say, wholesome substances can be a problem. They are not allowed off the school premises at lunchtime but many skip lunch altogether because the kitchen can't cope, which is just as harmful as carb-loading at the chippie.

All the exciting news in food is happening with street vendors (see Eat.st for a shining example). Could fun, speedy, healthy "wagons" that pull up in the playground be the answer, if they can make the sums work?