Not far from the playing fields where an off-duty detective was shot by a suspected Republican assassination squad in Omagh last week is an area named Mountjoy. It takes its designation from Lord Mountjoy, a general under Elizabeth I, who defeated the last Irish chieftain in the town in 1602. That Omagh is in the headlines in 2023 is a matter of bitter regret for everyone who lives there. The reason is political and beyond their control, just as the battle would have been more than 500 years ago. One thing is clear as UK Prime Minister Rishi Sunak unveils his efforts to negotiate with the EU over the post-Brexit Northern Ireland Protocol: his government is failing an Omagh test, by which I mean losing the struggle to keep the divided region peaceful. And by the time the politicians mark the 25th anniversary of the landmark peace deal, known as the Good Friday Agreement, on April 10, the idea of celebrating it – US President Joe Biden is rumoured to be keen to travel there – is likely to be untenable. The attack on Detective Chief Inspector John Caldwell last week revives uncomfortable memories of the 30-year-long Troubles that saw terror campaigns kill thousands in the British-ruled region. Mr Caldwell was undoubtedly a proud local man who was with his son at football practice on winter evening. As the BBC reporter on the scene noted, there were scores of teenagers at the scene playing all manner of games. As the secretary of the Beragh Swifts team said, this was a man engaged in the most routine of youth football coaching. "It was such shocking news that someone – out where there should be enjoyment – that anyone would walk up and try to take your life,” said Shirley Hawks. “It just takes us back.” Omagh was the place where the last shooting of a policeman in Northern Ireland occurred, when Ronan Kerr was murdered in 2011. A factor making the attack on Mr Caldwell somehow more shocking is that two of the handful now held were picked up on suspicion in 2011 after Mr Kerr’s killing. It also bears reminding that the quiet country town at the confluence of two rivers was also the scene of the worst death toll during the Troubles when 31 were killed in 1998. These had been days of celebration in Omagh. One of the local schools won the prestigious Gaelic football championship earlier this month. Speaking after the game, the coach of the winning team talked about how he had been at the school, won the same trophy in his time, gone away and trained but came back to teach in his old classrooms. Omagh is that sort of tight-knit place and, despite the underlying divisions in the town, people from every walk of life will share the pain of Mr Caldwell’s family. When the news of the shooting broke, Arlene Foster, the former first minister of Northern Ireland, was speaking on a UK-wide news programme. Like the son of Mr Caldwell, she was the child of a policeman who looked on as her father was shot in the head in 1979. “John's son isn't the first child who would have witnessed the attempted murder and even in some cases the murder of their parent, and it's something that never leaves you,” she said. “You just live with it, quite frankly." “Live with it” has been the message from Ms Foster’s fellow hardliners campaigning against the UK’s protocol deal with the EU. Their determination to uproot the arrangement with Brussels, designed to protect the All-Ireland links that have been built under peace, has intensified tensions in Northern Ireland. As history shows, the rise of frustrations and resentments is the very thing that creates the seedbed for violence in Northern Ireland. Mr Sunak has struggled for weeks to launch his reshaped protocol deal with the EU, as Ms Foster’s Democratic Unionist Party (DUP) and Brexit-backing Conservatives fight for the whole thing to be scrapped. The cost in Northern Ireland has been new division. A poll released last week showed that the majority – 53 per cent – in Northern Ireland back the protocol as an appropriate means for managing the impact of Brexit. There is already democratic consent built in the EU-UK agreement as the local assembly is due to vote on its operations at the end of 2024. The catch here is that because of the DUP and its political stance, the Belfast assembly has not sat since the last election. According to the poll, a majority of 51 per cent want representatives to vote in favour of the protocol when the time comes, while only 41 per cent wants a vote against. The real kicker in the poll was that a mere one in five respondents view the protocol as their top-ranked concern. With the situation inflamed, a policeman fighting for his life and a town thrown back on its nerves, Mr Sunak has carried on with careful efforts to lure the DUP out of its post-Brexit meltdown. Addressing the real Omagh test of providing unifying and healing leadership that is focused on eliminating the social and political issues festering since Brexit is not on the table from the British prime minister. Even if he can get his protocol deal over the line, Mr Sunak is nowhere near resolving the serious dangers facing Northern Ireland.