Ours is the first meta-analysis synthesizing results from econometric studies carried out in the UK to assess the size of the gender wage gap (GWG). Drawing on 90 primary studies published between 1974 and 2024 we assess trends in the gap and identify the substantive and methodological factors that explain variance in results across studies. Expressed relative to men’s earnings, the raw GWG averages 25 log points but falls to 13 log points when adjusting for covariates. There has been convergence in the mean wages of men and women at a rate of about 0.3 percentage points per annum, most of which reflects change in the characteristics of workers and their treatment in the labour market rather than differences over time in study characteristics. There is substantial heterogeneity in the size of the GWG by year of observation, worker type and research design, although differences in the size of adjusted GWG by study design are not as large as most economists might imagine.