As Labour leadership contenders muse about rolling back Brexit, the one U.K. region that retained unfettered access to the European Union¡¯s market for goods is thriving.

Northern Ireland has enjoyed bumper economic growth at twice the pace of the rest of the country in recent years, with many businesses getting the best of both worlds by having one foot in the British market and another in the EU one. And while violent protests over an asylum-seeker arrested in connection with a brutal stabbing attack in Belfast has prompted fresh criticism of the open border with the Republic of Ireland, there¡¯s increasing evidence the region¡¯s special status is helping businesses there.

That¡¯s the experience of Crushing Screening Parts Ltd. in Maghera, Northern Ireland, which provides parts for rock-breaking equipment used in mining and quarrying. Ten years on from the seismic 2016 referendum on Britain¡¯s EU membership, the local economy¡¯s privileged access to EU goods markets has proved a boon.

¡°The Northern Irish economy is on the front foot for the first time in my lifetime,¡± said Michael McGrath, the company¡¯s owner. ¡°We¡¯re in the world of machine breakdowns and people want machines fixed fast.¡±

McGrath said his company can deliver a hydraulic component to Berlin for 10 a.m. the next day with no paperwork, whereas rivals in Great Britain would have to use customs brokers and navigate bureaucracy in a process that might take them two days.

The Northern Irish statistics office estimates that economic output has grown 6% since 2022, more than double the 2.8% pace for the U.K. as a whole. The region has also seen bumper property price growth while the rest of the market stagnates, with house valuations up 7.4% in the year through February.

Meanwhile, consensus has grown among academics, politicians and voters that Brexit has damaged the U.K.. Bloomberg Economics has estimated that leaving the EU may have already cost the British economy between 2% and 4% of output over the long term.

With polls suggesting a majority of Britons want Brexit reversed, Labour politicians jostling to replace Keir Starmer as Prime Minister have talked up the prospect of much closer ties with the EU. Former Health Secretary Wes Streeting has argued for returning to the EU, calling Brexit a ¡°catastrophic mistake.¡± Greater Manchester Mayor Andy Burnham, who is seen as the front-runner to oust Starmer should he win a special election to reenter parliament next week, has been more cautious, while conceding there is a case for it in the long run. Both men have said they¡¯ll stand if a leadership contest is triggered.

Tax data suggest Northern Ireland is the only U.K. region to see an increase in the number...