John Mackintosh, incorporated in 1899, emerged as one of Britain's major confectionery firms, gaining national prominence through the manufacture and marketing of distinct products. A number of interrelated factors marked its growth. Dominated by a single family, the motivations and contributions of its leading members were formative, and its history inevitably engages with debates on Britain's “personal capitalism” and its failings. Considering the importance of marketing to a consumer products manufacturer, capabilities in this critical function are entangled with issues of ownership and management. During the 1930s, the firm ended its reliance on toffee lines, replacing them with innovative, highly advertised brands that mixed toffee with chocolate. These product breakthroughs were fully exploited in the postwar consumer boom. The timing and nature of Mackintosh's achievements can be compared to those of its rival, Rowntree, but there were important differences in their implementation. The story of this firm is an important addition to the history of the British confectionery industry and its development, offering insights into the evolution of marketing techniques. The case of Mackintosh is additionally useful because it clearly reveals an unexplored theme. A long-term perspective on its growth highlights the distinction between “early” and “mature” markets and shows how changes in demand influenced, and then tested, the efficacy of marketing approaches.