In parallel to the emergence and subsequent dominance of Thatcherite ideology across the realm of British politics from the mid-1970s, the UK Labour Party’s social and welfare policy agenda reacted and evolved for over two decades, a simultaneous and often futile process that occurred largely during a sustained and frustrating spell in political opposition. This convoluted policy journey therefore correlated with the party’s struggling electoral fortunes in the context of four successive general election defeats, before eventual convincing victory in 1997. This article seeks to illustrate that even before losing office in 1979, the Labour Party struggled to adapt to the advent of the New Right, facing hard structural policy-making constraints, with subsequent electoral defeats occurring amidst a more volatile public mood, changing demographics and social values, and a shifting social and economic model. In explaining how and why this happened, the article suggests that this was a critical evolutionary process for Labour, with flexible pragmatism and political necessity often eclipsing fading ideological imperatives, as the party sought electoral credibility and a route back to government. Consequently, by 1997, due to various factors, Labour’s social and welfare policies had been transformed beyond all previous recognition.