Social Geographer Ceri Peach estimates that the number of people in Britain born in the West Indies grew from 15,000 in 1951 to 172,000 in 1961. In 1962, the UK enacted the Commonwealth Immigrants Act, restricting the entry of immigrants, and by 1972 only holders of work permits, or people with parents or grandparents born in the United Kingdom, could gain entry – effectively stemming most Caribbean immigration. Despite the restrictive measures, an entire generation of Britons with African-Caribbean heritage now existed, contributing to British society in virtually every field.