LONDON, UNITED KINGDOM - MAY 21:  Prime Minister David Cameron delivers a speech on immigration at the Home Office, on May 21, 2015 in London, England. Despite pledging in 2010 to reduce migration numbers to less than 100,000, new immigration figures reveal that net migration to the UK reached 318,000 last year, the highest in a decade, increasing more than 50% in 2014. The Prime Minister has today unveiled measures to tackle illegal immigration, which include seizing wages. (Photo by Matt Dunham - WPA Pool/Getty Images)