This paper is an observational study of particular historical trends in mortality inequality within Great Britain, comparing England and Wales with Scotland for the period 1925–2005. The inequalities in mortality within Great Britain have become more apparent over time. Growing inequality in premature mortality in Britain affected young Scottish men most severely after 1995. It would appear that something dramatic happened to the Scottish population in early 1970s which accelerated these broad and very important mortality differentials within Great Britain. The divergence in mortality within Great Britain is notable in successive male cohorts and to a lesser extent in women.