Should there be compulsory ID cards? A new study has found almost one in seventy people across the UK may be in the country illegally. Some say it is time for drastic measures.
Up to one in 12 illegally in London

Glossary
Visa - An official document permitting someone to legally enter and stay in a country.
Overstayed - Someone who has stayed longer in a place than they are allowed to. Often a tourist or student visa will allow someone to stay in a country for a number of months or years, but they then must leave or change to a new visa.
Asylum - When a state agrees to shelter somebody who is fleeing dangerous circumstances. The right to asylum is protected in international law by the 1951 Refugee Convention.
Gig economy - A way of working based on temporary jobs or casual part-time work rather than permanent jobs.
Modern slavery - When an individual is exploited by others for personal or commercial gain. They can be tricked, coerced or forced to lose their freedom. Sometimes modern slavery involves human trafficking and often forced labour.
Trafficked - When people are bought and sold, often to become slaves or forced workers.
Tony Blair - Tony Blair was the leader of the Labour party. He was British prime minister from 1997 to 2007.
Exacerbate - Make worse.