UK Immigration Service
The United Kingdom Immigration Service (previously known from 1920 to 1933 as the Aliens Branch and from 1933 to 1973 as the Immigration Branch) was the former operational arm of the Immigration and Nationality Directorate, part of the Home Office. It was responsible for the day-to-day operation of front line UK Border Controls at 57 designated ports under the Immigration Act 1971, including airports, seaports, the UK land-border with Ireland and the Channel Tunnel juxtaposed controls.