This article examines the secular trends in the overall association of parental divorce (or separation) and children's educational attainment at school-leaving age during the period spanning a quarter of a century since the second world war in Britain. The study presents a reanalysis of data from the three British birth cohorts which studied children born in 1946, 1958 and 1970. Equivalent educational attainment at the different time points is defined relative to the population distribution at the time, using the median level. The relative risks (with 95 per cent confidence intervals) of lower than median educational attainment associated with parental divorce (or separation) are 1.3 (1.2 to 1.5), 1.4 (1.3 to 1.5) and 1.4 (1.3 to 1.5) for the three cohorts respectively. These results refute the commonly held opinion that the effects of divorce on children have attenuated with the increasing prevalence of divorce.