The list of her mistakes is not short. She did not have to trigger Article 50, the legal mechanism for leaving the European Union, before making a plan on how to do so: That decision set a two-year clock ticking and has resulted in the cliff edge the country would have reached on the 29th of this month if an extension had not been granted. She did not have to call an unnecessary parliamentary election in 2017, one which resulted in the loss of her majority and forced her to rely on a small, radical, Protestant Northern Irish political party, as well as the extreme anti-European faction within her own party, in order to stay in power.
But her errors go even deeper. In fact, all of the events of the past two years have been shaped by a decision she made, by herself, following bad advice, at the very beginning of this process. Remember that the British did not vote for any particular form of Brexit: Thanks to Cameron’s simplistic, open-ended referendum question, they chose to “Leave” the European Union but did not express any view on what should happen next. When she took office, May could have observed that the vote was very close, that Britain’s commercial and political ties to Europe were strong, and that it would make sense for the United Kingdom to stay within the single market, the pan-European free-trade zone that Britain itself did so much to create — or at the very least within a customs union.
Instead, she chose to leave both of those institutions, a decision that immediately triggered the problem of the border between Northern Ireland and the Republic of Ireland, which was eliminated thanks to E.U. trade treaties but will, if customs barriers are put in place, need to be built back.