Pliable teen Marigold McAllister keeps the wrong sort of company

Nearly everyone who comes across 15-year-old Marigold McAllister agrees that she is "a very nice girl". This opinion is corroborated by both her mother and the end-of-term reports that accompany her home from the private school in Hampshire at which her parents installed her four years ago. "Once again, Marigold has excelled herself at her studies," the headmistress declared in her precis of the summer's achievements, before adding, somewhat cryptically, "but I would remind her, once again, that a girl will also be judged by the company she keeps."

And what sort of company does Marigold keep? Mrs McAllister is a liberal-minded woman and would not dream of using such a prejudicial phrase as "bad lot", but it is a fact that her daughter's friendships invariably fill her with horror. Even at primary school, her first decisive act was to bring home for tea a wide-eyed slattern called Sandra, who ate nothing but chips and, shortly after her departure, was discovered to have lit a small fire in the back garden.

Ten years later, the social level of Marigold's attachments may have risen a little – the fees at St Brynhilda's start at £15,000 a year – but the taint of undesirability remains. Just now Marigold is spending the considerable part of her leisure time not devoted to piano lessons and French conversation with an overly made-up trio named Jo, Cassie and Pippa – bold-faced hoydens, her mother sadly acknowledges, whose school skirts always seem to be three inches shorter than anyone else's and whose visits to the family home are marked by Mrs McAllister locking up the drinks cabinet and sniffing the air for marijuana.

There are times when Mrs McAllister attempts to stem this devitalising tide by producing some demure and blameless girl whom she is sure her daughter will want to befriend. It is never any good, and neither is the faint air of expostulation that Mrs McAllister has begun to bring to discussions of Marigold's social life. "I really can't imagine, darling, what you see in Cassie,"she will remark, only to be told that Cass is all right really, mum, and doesn't drink nearly as much as people imagine. It is a great pity, Mrs McAllister sometimes reflects, that she should have fallen victim to the great unwritten law of child-rearing: that you can raise, clothe and educate your offspring as you wish, but you cannot choose their friends.