(FILES) Demonstrators hold up Pro-Europe placards at an anti-Brexit protest in Trafalgar Square in central London on June 28, 2016. June 23, 2026 marks 10 years since the UK voted for Brexit, upending the country's politics and triggering fraught negotiations that finally concluded when it left the European Union in January 2020. Immigration, trade and the economy were all key issues during the Brexit campaign. (Photo by JUSTIN TALLIS / AFP via Getty Images)