The Children Act 1948 was UK wide. It stated that it was the duty of local authorities to receive into care any child who was without parents or whose parents could not care for him for any reason, if it was in the interest of the child’s welfare. It led to the establishment of Children Departments (also known as Children's Departments) for the first time across the UK, building on findings from both the Clyde Committee (in Scotland) and the Curtis Committee ( England and Wales), which in itself followed on from the Monckton Report into the death of foster child Dennis O'Neill.
The legislation did not, however, at this time translate into significant increases in staffing, or of professionally trained staff. Although each local authority was, by law, to have a Children's Officer, this was, for many authorities, a part-time position, and in the city of Dundee, it was actually shared by the person responsible for public cemetries! So it was left to voluntary organisations to continue to provide most of the social work intervention with children, and in Scotland, it was the Royal Scottish Society for the Prevention of Cruelty to Children that did the child protection work (the organisation is now called Children 1st).
Further reading: Bob Holman's book, Champions for Children: The lives of modern child care pioneers, Policy Press, 2001, tells the story of three early children's officers.