Britain went to the polls in a referendum on EU membership in June 2016. Photo: Daniel Leal-Olivas/AFP

Then prime minister David Cameron campaigned hard for Britain to remain within the EU. Photo: Geoff Caddick/AFP 

Former London mayor Boris Johnson was a key figure in the campaign to quit the EU. Photo: Leon Neal/AFP

A dog waits for its owner to cast their vote in Britain’s EU referendum outside a London polling station. Photo: Adrian Dennis/AFP

In the June 2016 referendum, 52 percent voted for Britain to leave the EU. Photo: Glyn Kirk/AFP

David Cameron resigned as Britain’s prime minister after the shock referendum vote. Photo: Geoff Caddick/AFP

Theresa May became prime minister just weeks after Britain voted to leave the EU. Photo: Oli Scarff/AFP

Then UK Independence Party leader Nigel Farage meets EU Commission chief Jean-Claude Juncker in Brussels days after UK’s Brexit referendum. Photo: John Thys / AFP 

Organisers said up to a million people joined an anti-Brexit rally in London in March 2019. Photo: Daniel Leal-Olivas / AFP

European Council President Donald Tusk holds the formal notice launching Brexit. Photo: Aurore Belot/AFP

British Prime Minister Theresa May formally launched the process of exiting the EU at the end of March 2017. Photo: Justin Tallis/AFP