Addition is a trojan horse of a novel. It has a cutesy cover (featuring amorous toothbrushes), a kooky love story and a ‘hot’, wisecracking blonde heroine. There is a ‘hunky’ Irish love interest, Seamus O’Reilly, and a push-pull attraction of opposites between the romantic leads – whose first meeting, of course, is a witty war of words. But the heroine, Grace Vandenberg, is no ditsy Bridget Jones everywoman. She is an obsessive-compulsive counter who lives on a dis-ability pension; her only friends are her mother, her sister and her niece. And she is devastatingly smart.

So far, so quirky – but the really transgressive thing about Addition is the way it questions conventional lives. Most single-girl chick-lit (as opposed to yummy mummy chick-lit, an entirely different category) reaffirms that it is okay – even lovable – to carry a few extra kilos, to like chocolate, be born to shop and to dream of a big white wedding. It is all right to dream of a sexy boyfriend (and maybe a career to match) instead of the fabled wedding. Generally, it is all about celebrating the average.