A 'turn-up for the books' comes from gambling, not literature

Forsyth opens by dismantling a common misreading: the phrase "turn-up for the books" has nothing to do with literary books at all — it comes from bookmakers, the Victorian-era betting professionals who recorded wagers in a physical ledger, or "book." A "turn-up" in racing slang meant an unexpected stroke of luck, specifically when a long-shot, unbacked horse against short odds won a race, meaning the bookmaker didn't have to pay out much because almost nobody had bet on that outcome.

The deeper logic he unpacks is almost mathematical: gamblers rationally back favorites with short odds, since long-shot wins are rare, so when a heavily unbacked horse actually wins, it's a genuine rarity worth naming — a happy surprise for the bookmaker specifically, not the general public.

This sets the book's method from its very first page: take a common phrase, trace it to a specific historical trade or practice most people have forgotten, and show that the metaphorical meaning we use casually today has a concrete, almost technical origin buried underneath. Takeaway: an idiom's plain meaning often hides a forgotten, very literal original context.