E Jane Dickson: However liberal one's stance, the open sale of psychotropic treats is an abomination

At Camden Market, Clara's pocket money is burning a hole in her pocket.

At Camden Market, Clara's pocket money is burning a hole in her pocket. "I think," she says, having considered and rejected an ocarina, a furry photo frame with a picture of Prince Charles in it, and a sparkly Perspex mobile, "I'll buy a toadstool. It'll be great for the Fairy House."

The Fairy House is a marvellous construction, some years in the making, fitted out with pixie-sized cardboard sofas, cotton-reel tables and crinkly sweetie-paper curtains. We are forever on the lookout for the ne plus ultra of Little Folk furnishings that will attract real fairies (who are notoriously style conscious), but I am taken aback to be dragged over to a stall displaying many varieties of hallucinogenic fungi.

"Look, Mum," urges Clara. "They're magic. It says on the sign." There are indeed supersized, plastic display models of "magic mushrooms" laid out, at child level, along the stall, alongside cannabis-flavoured lollies, elaborate glass bongs and small bottles of commercially produced chemical stimulants. "I'm sorry, darling," I tell Clara, "but these wouldn't be suitable for the Fairy House at all. They're drugs and they're very dangerous. It's a disgrace," I go on, glaring hard at the stallholder, who clearly couldn't give a fairy's fart for my parental outrage, "that they should be on sale at all in a place where children come to spend their pocket money."

Clara, who knows as much as nine-year-olds, regrettably, have to know about drugs these days, is suitably shocked; she's rather more concerned, however, that I am going to make one of my scenes, and is keen to move on. Conor, on the other hand, is perusing the items on offer with some interest. "Can I buy a pipe?" he asks. "I'd never use it for drugs, Mum," he adds, just to reassure me.

I'm not inclined to view this kind of thing as part of colourful cosmopolitan life. The relaxation of laws relating to the sale and possession of cannabis in parts of London is a complicated issue and not one that I want to have to discuss with my children on a Sunday afternoon out. And however liberal one's stance, it seems to me that the production, let alone the open sale on the high street, of cannabis-flavoured lollipops and other little-league psychotropic treats is an abomination.

Happily, perhaps, my mutterings are drowned out by the background noise of barkers promoting less contentious wares. Con and his friend Thomas have been amusing themselves by marking a trail on the ground with pieces of flint, and caught up by the spirit of entrepreneurialism, have decided to market the stones they have collected on the way as "wild chalk".

"Wild chalk for sale, only 50p!" they call, as I tow them through the crowds. The boys are outraged by the lack of customers for this interesting commodity. I outline the principles of the free market, pointing out that people don't generally want to pay good money for rubbish, and hope to hell that I'm right.