Great Britain joined the European Union. The British were split on whether to join the Union. In 1975 the British held a nationwide referendum on the Union. 67 percent o the British voted in favor of being part of the Union. In 1992 the Maastricht Treaty transformed the EU from an economic union to a more integrated union Great Britain did not join the with many other states in adopted the Euro to replace its currency. The stronger Union began to foment resentment among some Britains. Rising immigration from some of the poorer EU countries and refugees from Africa and the Middle East increased that resentment.
Conservative Prime Minister David Cameron promised in the 2013 election that if the Conservative Party won he would hold a national referendum on whether to stay in the Union. He was sure that the referendum would vote to remain.
On June 23, 2016, a referendum was held. When the results were announced most Britains were shocked. 52.89% voted to leave the Union and only 48.11% vote to stay. 17,410,742 British citizens had voted to leave the EU, while 16,11,241 voted to stay. Four million Britain signed a petition calling for a second referendum claiming that many of those who voted to leave did not want to leave but were merely registering a protest vote. The government rejected the petition. At this point, Cameron resigned and was followed by Theresa May as the new Prime Minister.
On March 20, 2017, Great Britain officially began the process of leaving the Union by invading Article 50 of the Treaty of Europe. May held a snap election which changed very little. May negotiated an exit agreement with the European Union but it was rejected three times by the Parliament. Different factions opposed different elements of the agreement. Britain asked for two delays which were granted by the EU. After the parliament again rejected the agreement Theresa May resigned and Prime Minister and was replaced by Boris Johnson and early and vociferous supporter of Brexit. He quickly called new elections and the Conservative Party he led won an overwhelming victory.
An exit agreement was approved by the EU and the British Parliament. It called for Britain to officially leave the EU on February 1, 2020. That agreement, however, provided a one year transition for all of the economic aspects of Brexit to be negotiated and take effect.