Drawing on signalling theory, this study aims to fill a gap in knowledge by examining the effects of celebrity trust on advertising credibility, brand credibility and corporate credibility, both directly and based on the moderating variables of age, gender and ethnicity. The research has three objectives: (i) to explore the effects of celebrity trust on advertising credibility, brand credibility and corporate credibility; (ii) to explore the effects of celebrity trust on advertising credibility, brand credibility and corporate credibility, based on the moderating effects of consumer demographics; and (iii) to explore the effects of the other constructs on each other. A survey of 625 respondents was conducted in London. The results show that celebrity trust has a positive effect on both advertising credibility and brand credibility, and that these effects are moderated by consumers’ ethnicity, with no effects of age or gender. The significant implications for managers and researchers are highlighted.