1. Cameron promised a referendum to deal with Conservative party divisions and UKIP threat
2. 2016 referendum resulted in vote to leave EU
3. David Cameron resigned as PM
4. Theresa May became PM and triggered Article 50
5. May called a general election but lost majority
6. Boris Johnson became PM, prorogued parliament, negotiated withdrawal agreement
7. UK left EU single market and customs union on 31 Dec 2020