Brexit time—get it? Armstrong’s new book focuses on “how, why and when” the UK leaves the European Union.

“The aim of Brexit Time is to explore why, how and when the UK is leaving the European Union,” writes Kenneth Armstrong in his new book. This is clearly no small task: is the author up to it? As the Director of the Centre for European Legal Studies at Cambridge, he is certainly well qualified.

Armstrong sums up the Brexit debate from the time before the referendum to more or less the present moment—and then looks to the task ahead. “This is not a book about whether withdrawal from the EU is a good or a bad thing,” he tries to reassure us. Rather, it is an explainer that lays out clearly the terms with which we are rapidly having to become familiar: transitional Brexit deals, the European Court of Justice, the European Medicines Agency, Repeal Bills, Henry VIII powers (yes, really). The whole Brexit issue is expertly picked apart, the political and legal analysis of this constitutional leap into the dark is genuinely insightful.

There are flaws. Armstrong latches onto “time” as a running theme, but it feels a bit forced. Consider, for instance, the section titles: “Time of Brexit,” “Time for Brexit,” “Time to Brexit.” The difference between these is not immediately obvious, at least not to me. At one point he writes: “Choices are made that shape Brexit… they are choices in time, and of time.” Perhaps not the author’s finest moment.

But leaving aside the rhetoric, the substance is solid—and the book arrives just as it is most needed. Our departure from the EU looks more complicated by the day. Far from swaggering through EU negotiations as the Brexiteers assured us, little progress appears to have been made. So despite the author’s pretension to neutrality, the facts point in one direction: ministers take note, Brexit will be one hell of a challenge.

Brexit Time: Leaving the EU—Why, How and When? by Kenneth Armstrong  is published by Cambridge University Press (£17.99)