By supporting Remain, Ulster Unionist leader Mike Nesbitt has emerged as the champion of Northern Ireland's interests. But how did the First Minister get the EU poll so badly wrong, asks Alban Maginness.

Mike Nesbitt called it right on Brexit, as far as the majority of people in Northern Ireland were concerned, and Arlene Forster called it wrong. But why did she make that political blunder?

Arlene Forster was a successful Enterprise Minister. She performed well, was energetic, committed and hard-working. Given our own difficult economic circumstances, she was reasonably successful in attracting foreign direct investment and job creation across a range of sectors. She knew the challenges and she knew our shortcomings, in particular our remoteness as a region in the UK and Europe.

She knew our advantages as having a young, educated and skilled English-speaking workforce within the European Union. She knew that being in the EU attracted foreign investors, in particular the Americans. She also knew being a member of the EU was a highly favourable factor in a fiercely competitive international investment market.

As minister, she was also aware of the advantage the Republic had in attracting overseas investment while being a member of the EU and having the lowest rate of corporation tax in Europe. This advantage she did much to address by helping to achieve political consensus on a lower rate of corporation tax for Northern Ireland, but within the EU.

Given her unique understanding of our objective economic position and given the obvious necessity in maintaining the status quo for Northern Ireland and, thereby, staying within the EU, why did she campaign to leave? Why did she effectively vote for economic suicide?

I understand she had to let some of the headbangers among the DUP take a Ukip approach. Some letting-off of political steam at Westminster is understandable, but at home it is a different call - especially given the specific interests of local unionist businesses and unionist farmers.

Arlene should have realised that there was little political advantage in supporting a Brexit campaign in which the damage to the Northern Ireland economy would be so severe.

As First Minister for all the people of Northern Ireland, she could have rightly adopted a position of political neutrality, allowing the local campaign to proceed and be in a position to accept the majority decision of the people in Northern Ireland, either for or against.

Now, as a Brexit-supporting First Minister, she has compromised herself. She is, frankly, in a very difficult position to properly represent the vital interests of the people of Northern Ireland in negotiations with the British Government, the Republic and with the EU itself.

But leaving aside these important economic arguments, from a purely unionist point of view, it was unwise to campaign to leave, when she was aware that a successful Brexit campaign would allow the SNP Government in Scotland to trigger another independence vote, thereby threatening the very stability of the UK itself.

Surely, provoking that obvious SNP threat did not serve the wider unionist cause well and, if properly considered, would surely have given the DUP cause to consider not going down the path of Brexit?

Arlene's strategy was short-sighted and foolish from a unionist point of view. Instead of strengthening the UK, the Leave vote has weakened the political muscle of the Union, with very serious implications for unionism here if Scotland were to opt to leave the UK in a year or two. Arlene may bluff and bluster and contend that all will be well, but this is a defining moment, both politically and economically, bringing in its wake a stream of unintentional consequences. This is a political earthquake with any number of political aftershocks.

The future is uncertain, as is the present, and it would be a foolish person who could predict what will now happen.

But what is certain is that Mike Nesbitt made the right call for the people of Northern Ireland. He has been clever in backing Remain and, thereby, identifying with the real economic interests of Northern Ireland and the business and farming interests, in particular.

He has outflanked the DUP and positioned himself as the champion of the Northern Ireland majority interest. From a position of strength, he can command the political debate around Brexit, demanding to know what Arlene and Martin will now do to protect the legitimate interests of the people.

He can ruthlessly scrutinise in depth any attempts by the Executive to cope with the new dispensation. With the SDLP and Alliance, he can frustrate Westminster's anti-democratic attempts to take Northern Ireland out of the EU by voting against any legislative consent motions from Westminster to the Assembly, which may be necessary to bring about the legislative decoupling of the UK from the EU. Sinn Fein will find it impossible to avoid supporting such moves.

In the same way that the Scottish parliament may attempt to veto Brexit in Scotland, the Assembly may make life extremely difficult for the self-serving Boris Johnson and his irresponsible and reckless cronies.

Belfast Telegraph