1. Buy good companies, do not overpay, do nothing
Smith's framework reduces to three rules, repeated in every Fundsmith annual letter since 2010 and inscribed on the firm's website as the operating mantra. Buy good companies means owning businesses whose underlying economics are structurally superior: high returns on operating capital, sustained over many years, financed primarily from retained earnings rather than external capital, with growth that is organic rather than acquisition-driven. Do not overpay means having a valuation discipline that rejects names trading at multiples that imply heroic future assumptions, even when the underlying business is otherwise attractive. Do nothing means running the portfolio with an annual turnover rate of around 10 percent or less, which is roughly an order of magnitude below the typical mutual-fund average. The compactness of the three-rule framework is itself part of the methodology. Smith argues that complex investment rules invite cognitive overrides and behavioural failures, while simple rules consistently applied compound advantage. The Fundsmith Equity Fund's twelve-year returns from 2010 to 2022 (roughly 14 percent annualised in GBP versus 9 percent for the MSCI World) are presented in the annual letters as the empirical case that simplicity, properly applied, outperforms complexity.