Tomboy fashion has changed a great deal over the years. Once upon a time, if you had an inkling that you were into more masculine clothing, you'd have two options: actually wearing men's garments or settling for some pretty below-par "mannish" staples like baggy boyfriend jeans or boxy shirts. These days, though, stealing from the boys has become an artform—both in terms of womenswear designers creating more and more female figure–friendly menswear-inspired garb and in terms of the rules of styling them.

One fashion commentator, Navaz Batliwalla—the writer and blogger behind Disney Roller Girl—has hit this nail on the head in her recently released book, The New Garçonne (£13). It's a celebration of modern tomboy style, where the rules are meant to be broken, and expresses that just because you're wearing a suit doesn't mean you have to abide by the laws of shirt + flat shoes + tie + no makeup. It's what she also dubs "gentlewoman style": Think of dapper women who rely on the quality and heritage of perfectly made pieces, like fine penny loafers or a sharp Savile Row suit, and "who embody a quietly assured, masculine-feminine style."

Throughout the past decade's street style explosion, it could be easy to overlook the subtle garçonnes for the all-guns-blazing drama of a sweeping, glittering gown with the Champs-Élysées for a backdrop. But delve a little deeper into the archives and you'll see that there's been a steady increase in industry women eschewing the frivolities of flirty, ultra-pretty, whimsical fashion for the cooler tropes of the tomboy.