Zeynep Aziz
British Prime Minister Theresa May announced on 24 May that she would step down as Conservative leader after Parliament repeatedly rejected her Brexit deal.
What happened
May had negotiated a withdrawal agreement with the European Union but could not unite her party or build a Commons majority around it.
Why it mattered
Her departure opened a Conservative leadership contest and deepened uncertainty over how and when Britain would leave the EU.
Context and consequences
Boris Johnson later succeeded her, adopting a harder negotiating stance before securing a revised agreement.
