This paper investigates the ethnic and gender diversity of the corporate board of UK companies, placing particular emphasis on links to board size and industry characteristics. We employ a novel dataset that covers a large sample of UK PLCs and describes a director’s gender, ethnicity and position held. We find both ethnic and gender diversity to be very limited, and that diversity is somewhat less pronounced among executive positions. We find significant cross-sector variation in gender diversity, with an above average prevalence of women in Retail, Utilities, Media and Banking, while such variation in ethnic diversity is considerably less pronounced. Our evidence suggests that a close proximity to final consumers plays a more significant role in shaping board diversity than does the female presence among the industry’s workforce. We argue that this shows that board diversity is influenced by a firm’s external business environment and particularly an imperative to reflect corresponding diversity among its customers.