Gordon Brown and the Irish Taoiseach Brian Cowen are locked in talks in Stormont trying to prevent a collapse of devolution in Northern Ireland. The key issue is over the devolution of policing and justice powers from Westminster to Stormont, with Sinn Fein pushing for an immediate transfer and the DUP hoping to stave off the move until a later date. But why are these issues crucial to devolution? And why is a deal proving so difficult?

Firstly there is history. As ever with Northern Ireland, history is not too far from the surface. At the start of ‘the Troubles’ in 1969, the police were exclusively Protestant and the RUC was undoubtedly a repressive and partisan organisation. Within some sections of the nationalist community, there remains suspicion that the instruments of state retain a pro-unionist bias and so Sinn Fein really needs to secure a deal on the police. One of the largely unreported elements of the increase in radical republican violence in the past two years is that most of the targets were Catholic policemen, seeking to pressurise other Catholics out of joining the police force.

Secondly you have the actors involved. Sinn Fein and the DUP are at the extremes of the political spectrum in Northern Ireland. Both were sceptical about the Good Friday Agreement in 1998, with the DUP still maintaining their opposition to it. While they both accept the sovereignty of the devolved Parliament, they still harbour deep suspicion for one another. The fact that since 2007 they have been in cabinet together is nothing short of a miracle.

Thirdly there are the issues of the Orange Order marches. Until Wootton Bassett, to most British people marches seemed like non-issues, but in Northern Ireland they are deeply significant. Historically where marches went was as important as whether they happened. Orange Order (Protestant) marches often went straight through Catholic areas, provoking many violent clashes. The DUP wants to scrap the Parades Commission, which prevents some of the most controversial marches. But this brings the possibility of Orange Order marches through nationalist areas, potentially provoking tensions.

Fourthly there is an election coming up. Both the DUP and Sinn Fein do well when people are frustrated and neither can afford to be seen to lose face. So when the DUP talk about “unionist confidence” in the deal, they mean the importance of securing their core vote against the threat of the ultra-conservative TUV. Similarly Martin McGuinness cannot accept a watered-down version of devolution for fear of going back to his electorate branded a failure. The split in the Unionist vote means McGuinness has a real possibility of becoming first minister after the election. Ultimately, over a decade after 1998, the people of Northern Ireland still vote according to their religious affiliation. So the two parties are not fighting for the same electorate. These two electorates have different desires and both parties cannot afford to give too much slack.

Finally there is a fifth factor, a new one, which David Cameron may have inadvertently created for Gordon Brown. The Conservative Party is, of course, officially the Conservative and Unionist Party and senior Conservatives have reportedly been meeting with Unionists from both the DUP and the UUP. This will create fear in the nationalist community that if he won the election, Cameron would be partisan. Cameron would be advised to tread carefully.

A deal is not impossible and I am sure that both Gordon Brown and Brian Cowen will be working hard. But these are far from small issues and the collapse of Stormont, though not quite imminent, remains a realistic possibility.