Fictional girls' boarding schools are traditionally where spoilt little minxes go to be turned into well-rounded citizens through rigorous application of rags in the dorm, order marks, hockey and lacrosse. The stories have eternal appeal with their blend of fierce competition and loyalties plus a dose of character-forming nemesis, but the underpinning values might deter contemporary readers.

Kate Saunders's tale of the jolliest term on record at St Winifred's, 1935, offers everything you might expect from Angela Brazil with the advantage of the perspective of a "maggot" (new girl) from the present day.

Flora Fox is summoned to St Winifred's from 2010 after her dorm-mates-to-be dabble in the spellbook of the school's founder, who had some peculiar extra-currricular talents. This causes today's Flora to swap lives with a 1930s Flora, whose parents have shipped her off for an English education while they run bits of India.

Ms Fox, as spoilt and headstrong as they come, had been heading for a very hip boarding school where the head is called Jeff and the students can keep their phones and iPods and order takeaways. Her shock at entering a world without hair straighteners and laptops, where schoolgirls speak when spoken to, is well realised through faithful evocation of the sounds, smells and textures of the 1930s, from scratchy uniforms to carbolic soap and roaring motorbikes.

Flora gets into hot water for using the word "bollocks" but relishes saying "crikey" and "putrid" and lives in fear of "ponies". As a "colonial", Flora is a target of the school bully, Consuela, who is herself vilified because her parents are divorced.

Flora herself and her new gang of three  sweet, round and rather dim Dulcie, fiercely bright and bossy Pogo and spiky, charismatic Pete (Daphne)  are well-drawn characters whom we care about, especially Pete, who has elements of the Chalet School's Joey Bettany and Jane Eyre's friend Helen Burns and whose hard edges soften in a believable way. The core value of the St Winifred's girls  never let your friends down  is one that will not go out of fashion.

There is much to learn about 1930s girlhood, including the comforting function of sugar: in the absence of boys, nice clothes, ensuite showers and hair products, a girl could always count on the sweet shop and her tuck box.

The play on Flora's surname on the jacket design and chapter headings is the only jarring note: it sets up expectations that are not met in the story. However, this does not detract from the pleasures of a highly readable novel which combines wit and charm with hidden depths.