Using UK data supplied by universities, this paper confirms that women academics earn less than men, even after controlling for a range of covariates. Despite narrowing after 2004/05, the observed (unconditional) pay gap was still -0.089 in 2019/20, while the conditional pay gap was relatively unchanged remaining at around -0.050 in 2019/20. The results are consistent with the literature on why pay gaps might occur, with the key disparity occurring when women face a higher cost of investment and statistical discrimination, linked to bias, to achieve promotion. That is, the results presented here suggest that earnings gaps are significantly reduced when grade-balanced gender sub-groups are compared, suggesting conditional wage differences are more likely due to bias rather than any inherent differences in (research) productivity.