Industrial revolutiion saw many people move into the cities desperate for jobs-rural to urban migration occured.There were many pull factors including manafacturing jobs, better sanitation and heathcare.
Globalization
Urban areas expanded with the majority of factory workers living in slums.This was illustreated in Charles Dickens A Christmas Carol.
1970s-Today
Machines replaced people leading to de-industrialization.the UK went from 3000 coal mines to just 30. This caused mass unemployment in the 1970s-1980s as public businesses were sold .In 1983 a recession occurred causing unemployment to reach over 3 million in 1983.
Factories closed as products were made more cheaply overseas (growth of Transnational companies with factories overseas ( eg Primark).This led to the factories being aboned neglected and derlict.
Tertiary jobs replaced secondary jobs with many working in the service sector.UK is now a world leader in finance ,media, research and entertainment. For example researchers at Oxford created the COVID 19 vaccine Astra-Zeneca.