During the “Real Expedición Botánica al Virreinato del Perú”, 1777-1816, Hipólito Ruiz López (1754-1816), José Antonio Pavón Jiménez (1754-1840), Juan José Tafalla Navascués (1755-1811) and Juan Agustín Manzanilla (fl. 1793-1816) collected economically important specimens of anti-malarial cinchona bark (Cinchona spp.). In the 230 years since, these specimens have been dispersed across institutions in Spain, Britain, Germany and Italy. Two major sub-collections of these are found at the Real Jardín Botánico, Madrid, Spain (n = 243), and the Royal Botanic Gardens, Kew, UK (n = 188). The Kew collection arrived in Britain through Pavón and other Spanish botanists selling part of the collections. This study traces the history, trajectory and relationship of the collections between the two institutes.