It could be, as British Prime Minister Gordon Brown puts it, "the final piece in the jigsaw" puzzle. And, in this case, it is a rather expensive piece, indeed. If it is, however, the piece that makes the whole Northern puzzle knit together, then it will be well worth the cost.

Ever since Northern Ireland's power-sharing government came to power in 2007, a key question has been: When will the Stormont government take control of policing and judicial functions in the North?

Control over most of the typical responsibilities of government - like health, education, environmental, and financial matters - was transferred from Britain to Belfast when the Northern Ireland government took hold more than two years ago.

But for a variety of reasons, policing and judicial control remained in London, and while that arrangement suited some - mostly the North's unionists - the issue has become increasingly potent. To shelve it permanently would be to risk yet another toppling of the Belfast government that is seen as a key to peace and stability in the North.

So, in an environment where many nationalists wanted to see policing and judicial powers handed over to officials in the North, and nationalist and unionist alike worried about the North's economy and finances, Brown recently came forward with a deal that has something for everyone.

Along with the devolution of police and judicial powers, according to the deal proposed by Brown, would come a financial sweetener: $1.6 billion in additional funds over the next few years. On one level, the additional funding will serve to help pay for the new duties that the Belfast government would inherit, but on another level, the money clearly is intended to turn the heads of unionists who don't like the idea of a government that includes Sinn Fein republicans having anything to do with sensitive law and order functions.

Brown's offer came after intensive talks with the co-leaders of Northern Ireland's coalition government: Peter Robinson of the Democratic Unionist Party and Martin McGuinness of Sinn Fein.

In a letter to both men, the British prime minister wrote: "Together we have, I believe, achieved an outcome in which we each have confidence and which will ensure that when policing and justice powers are transferred, the Northern Ireland Justice Department will have a secure financial foundation which we all recognize is important in ensuring confidence in the policing and justice services across the community."

In subsequent comments at Westminster, Brown said: "I've been in touch with all party leaders in Northern Ireland and I am now sending to all of them ... my proposals for a financial settlement that is designed to make possible the completion of the final stage of devolution in Northern Ireland.

"Our aim is a peaceful, more secure, and more prosperous Northern Ireland."

The involvement of McGuinness, who now serves as deputy first minister of Northern Ireland, was an essential ingredient in working out a deal but it also illustrated why the issue was so sensitive and charged for so many people.

As a former top leader of the Irish Republican Army, McGuinness played a key role in the IRA's long campaign of violence, and many unionists, and probably a few nationalists as well, have qualms about McGuinness and other republicans being able to look into the files of the past and helping to make security decisions going forward. But in the end, it appears that the $1.6 billion payday may be enough to ease those fears and lead to the final element of devolution occurring early in 2010.

Speaking of the prime minister's proposal, McGuinness said: "People will see what is I think an incredible achievement against a backdrop of a very difficult financial position and see a great opportunity for us now to move."

Under normal circumstances, the justice ministry that would be created would go to a nationalist party, the Social Democratic and Labor Party, but the feeling is that the usual process for awarding ministerial positions will be sidestepped and this new position will go to the more neutral Alliance Party.

Because the devolution of policing and judicial powers is so seismic, and because so much money is on the table, Robinson and McGuinness took the unusual step of having the deal blessed by Conservative Party leader David Cameron, now considered likely to take over as prime minister next year. In the aftermath of Brown's announcement, Cameron voiced his approval. As one observer put it, Cameron countersigned Brown's check.

During the course of discussions, Cameron and McGuinness met, marking the first meeting of Conservative Party and Sinn Fein top leaders since Michael Collins and Austen Chamberlin huddled in 1921 during negotiations that led to the treaty that ended the Anglo-Irish War.

The better part of a century later, top officials from the two parties met in yet another effort to bring lasting peace to Ireland.