Theresa May’s appalling legacy will be the total destruction of the Good Friday Agreement

Stupid but industrious leaders are a danger to everyone. Pity us all that we lived through May’s prime ministerial reign

A German general once explained that he divided officers looking for promotion into four categories: the clever and lazy, the clever and industrious, the stupid and lazy and the stupid and industrious.

He said that the clever and lazy should be appointed to senior leadership positions because they could take important decisions without trying to interfere with the work of others. The clever and industrious should be made their deputies. The stupid and lazy should be sent to the front line, but the stupid and industrious should be pushed out of the army immediately because they are a danger to everyone.

Theresa May surely belongs to the fourth category of leader, because as prime minister she has shown that she has a lethal blend of tunnel vision and obstinacy that automatically produces ill-judged decisions.

Her list of blunders is too long to repeat here but must include her decision to treat the outcome of the EU referendum as if it was a decisive choice by the British people. The near dead heat should have meant that the wishes of both sides would need to be accommodated to stop existing divisions widening.

Instead, May acted like a British First World War commander at the Somme, pushing ahead regardless of actual circumstances. She triggered Article 50, taking the UK out of the EU without a plan; acted as if she had a parliamentary majority and had no need to compromise with the opposition; approached negotiations with the EU as if the balance of power lay in her favour and not in theirs; and she tried to bluff Brussels with the prospect of a no-deal Brexit far more damaging to Britain than the EU.

But the most poisonous part of her legacy is her feckless gutting of the Good Friday Agreement (GFA) of 1998, which ended 30 years of savage violence in Northern Ireland.

This was probably the greatest achievement of the British state for half a century, bringing to an end the Irish conflict, a running sore in English politics since the Tudors, through a compromise that everybody could live with. But, with May in charge, it has been a compromise that has shrivelled by the day.

Essential building blocks of the agreement, such as British government neutrality between nationalists and unionists in the North, were discarded because of the need for DUP votes in parliament. So too was cooperation with the Irish government to ensure the GFA was kept in working order.

Proponents of Brexit are strikingly parochial despite their boasted ambitions for global Britain, once it is freed from EU shackles. They were wilfully ignorant of Irish politics, fondly imagining that the nationalist population in border areas would tolerate cameras and electronic devices used to monitor the border where it cuts through their fields and villages. If customs are sent they will need police to protect them and the police in turn will need the army. We will be back to a militarised frontier.

A puerile suggestion is that the border be left to its own devices, forgetting that the EU is not going to tolerate a gaping hole in the tariff and regulatory walls protecting the customs union and the single market.

Why not tell the EU to just get lost, as many Leavers will argue? Because they will not “get lost”, and they are more powerful than we are with 47 per cent of British exports going to the EU and 15 per cent of EU exports coming to Britain.

For the DUP, the collapse of the GFA has no terrors because they voted against it and, whatever they may say publicly, they would like to see it stripped of any substance even if it still has a formal existence.

May either did not understand this or did not care, because she was fixated on her own unpassable Brexit deal that was voted down for the third time on Friday afternoon.

Right up to the end, she was trying to play what used to be called “the Orange card” as she struggled to persuade Tory Brexiteers to support her. Her meeting with them at her country residence Chequers last Sunday throws a bizarre light on what she thinks is happening in Ireland.

Press reports say that she spoke passionately about an enhanced threat of a united Ireland by claiming that the liberalisation of Ireland’s laws on homosexuality and abortion had made opinion in Northern Ireland more sympathetic towards union with the Republic. She pointed out that Sinn Fein is demanding a border poll and might win it because of the Republic ending its ban on abortion following a referendum last year – unlike the North, where it is still forbidden.

May went on to say that Northern Ireland leaving the union might have a knock-on effect on Scotland, where people “would demand the right to leave the UK and then the union would be destroyed”.

May is right in saying that Sinn Fein, which won more than two-thirds of the nationalist vote in the North during the last two elections, has been campaigning for a border poll since the Brexit referendum vote. It is also true to say that a few more voters who previously saw Irish unification as unity with a priest-ridden regressive state might change their minds.

But far more important in enhancing the prospect of a united Ireland is the UK leaving the EU which is contrary to the referendum result in the North where Remain won by 56 per cent to 44 per cent – something usually ignored in British media reports on the DUP.

Most important, support for Irish unity no longer looks like a retreat from the modern world into the Celtic twilight, joining a small weak regressive Irish nation state in preference to remaining in a powerful socially progressive Britain. Unification with the Republic now means reunification with the EU. Keep in mind that, while 88 per cent of nationalists voted Remain, the unionist vote was much more split, with better-educated middle-class unionists voting not to leave the EU.

It is important to draw the right conclusions from this. It does not mean that the unification of Ireland is close. Most Northern Irish Protestants remain adamantly against it. Plenty of Catholics still do not want it even if they are fewer in number than before. Many note the lamentable state of the Irish health service compared to the NHS. The Irish government does not want a referendum which would probably confirm the union and would certainly be highly divisive.

Nationalists and unionists in Northern Ireland tend to underestimate the toughness of the other side. The unionists did so in the past by trying and failing to impose their own exclusive rule, but the bulk of them are certainly not going to accept Irish reunification without a fight whatever the outcome of a poll.

What May and Brexit have succeeded in doing is putting issues like the Irish border and partition back on the agenda. The GFA compromise is all but dead.

Ireland has traditionally been Britain’s worst political ulcer and it has started bleeding again. The German general was right about the dangers of stupid but industrious leaders.