Final answer:
The Bevanites were the group advocating for a comprehensive 'cradle to grave' system of welfare, including free health provision, education, housing, and full employment, as part of post-World War II social reforms in the UK.
Step-by-step explanation:
The group that advocated for a comprehensive and completely free 'cradle to grave' system of welfare, health provision, and education, housing for all, and full employment was known as the Bevanites. Named after Aneurin Bevan, a prominent figure in the Labour Party, the Bevanites were influential in the establishment of the National Health Service (NHS) in the UK and were steadfast proponents of comprehensive social reforms following World War II. This group saw the provision of universal welfare and education as essential components of a just and equitable society.
Their advocacy fell in line with broader 19th and 20th-century movements in Britain that sought to respond to the issues of poverty, inequality, and workers' rights through social reforms and the development of the welfare state. This set the stage for subsequent developments in Britain's social policies, aimed at ensuring security and well-being for all its citizens from 'cradle to grave.'