One of the main reasons why almost 50% of British people have voted in favor of the UK leaving the EU is because they want the country to regain full control of its borders in order to reduce the flow of immigrants who They travel to the UK in search of work. You have all the information in: «The 'Brexit' in the United Kingdom: meaning, results and consequences«.
You have all the information in: "The 'Brexit' in the United Kingdom: meaning, results and consequences".