As I seem to find myself regularly explaining, Brexit is a process, not an event.
Which is all well and good, but also a bit problematic when you want to work out the appropriate context for that process.
At one level, it is evidently simply part of a much longer process of developing British European policy, certainly in the post-war period, but also arguably in the longue durée sense of British history.
At another, you can work from the rise of euroscepticism in the late 1980s in British politics and the ways that worked through to the present.
And on another, it’s that period since David Cameron made his commitment in 2013 to hold a referendum on membership.
Which level to approach it on depends, obviously, on what you’re trying to understand.
For the diagram below, I’ve focused on the period since the 2016 referendum, because I want to mark out the key moments in the formalised process of withdrawal, as far as we have them.
The diagram covers negotiations and the ratification of agreements, plus the start of implementation, on both sides of the table. I’ve also added in some key relevant moments in British politics, because those matter too in the story of this five and a half year period.
For those using this in teaching, you might consider how the domestic level and the negotiations marry together: periods of crisis in the UK often preceded the conclusion of talks, but does the former lead to the latter?
Likewise, you might use this to highlight the open-ended nature of this process. Implementation is not a steady state – as the Protocol discussions amply demonstrate – but rather a new set of negotiations and reviews that stretch into the distant future. As such, the question is how much as actually settled and how far does the system move from its January 2020 baseline?
Of course, that is another process.