The Liberators begins as thirteen-year-old Ivo Moncrieff arrives in London to spend the Christmas holidays with his aunt and uncle. Within a couple of pages he has been handed a mysterious, precious object by a stranger, and then witnessed said stranger's gruesome murder on a tube train. From then on the pace never lets up, the plot assembling itself around Ivo in a series of bold, interlocking coincidences, which might ring false in a different sort of book but don't jar at all in one which obeys the logic of dreams. Ivo's aunt, an artist, is painting a portrait of the attractive but dangerous Strawbones Luther-Ross, who, along with his brother Julius, heads a secret society called The Liberators which is preparing to overthrow the Apollonian forces of order and usher in an age of total, Dionysiac freedom. There is, of course, a rival secret society dedicated to stopping them, but it is comparatively weak, and it falls to Ivo and his new friends Miranda and Felix to try and defeat the brothers' plans.

The action of the book is non-stop (and sometimes violent), and the supernatural threat well-captured. What the Liberators stand for is not some unexplored concept of Evil, but total freedom, which sounds quite attractive until you stop and think about it. This Mr Womack manages to make us do in the brief pauses for breath between one adventure and the next. The magic which the brothers work is captured in quick, spare prose; precise descriptions of bizarre events spring from the well-observed London background in a way which makes them seem oddly vivid and believable. At times like these Mr Womack's writing put me in mind of Saki, or a cheerier M R James.

But what The Liberators mostly reminds me of is the books that I remember enjoying as a boy, and I think one of the reasons for that is the conspicuous posh-ness of its protagonists. Young Ivo Moncrieff is an appealing hero, but the very fact that he's survived to the age of thirteen with a name like Ivo Moncrieff tells us that the school he is on holiday from is nothing like the school I went to. His aunt and uncle hob-nob with politicians, while Miranda and Felix spend a lot of time trying to escape from their private tutor - probably the first time that that particular plot device has been used in a real-world setting for forty years.

As a child, I was quite used to reading about children who had cooks and nannies and went to stay with wise old relatives in rambling country houses. I suppose the authors I read had all grown up among the upper middle classes of twenty or more years before, and were drawing on their own childhood experiences, which were nothing at all like mine. But I never minded this, or thought it strange; indeed, the worlds these book-children inhabited, with their servants and boarding schools, their unknown freedoms and unimaginable self-confidence, seemed pleasantly fantastical; it was quite easy to imagine such children encountering ancient magic or setting off on unsupervised sailing holidays. Nowadays, although there are few occupations more deeply middle-class than that of the children's author, the protagonists of the books themselves tend to have backgrounds more like those of the 'average' reader, and if rich people appear at all then they generally turn out to be the villains. I wouldn't for one moment argue that the heroes of all children's books should be well-heeled, but it's refreshing to meet one who is, and quietly heroic of Philip Womack to challenge the prevailing fashion. I look forward to seeing what he does next.