The United Kingdom has one of the largest immigration detention systems in Europe, confining up to 4,000 people—including children—in detention every day under Immigration Act powers.
As of October 2016, the country’s immigration detention estate included nine “immigration removal centres” (IRCs) and a small number of residential immigration detention holding facilities. In addition, several hundred people are kept in prisons under Immigration Act powers awaiting deportation after having finished their criminal sentences.
https://www.globaldetentionproject.org/countries/europe/united-kingdom
