The Northern talks can be like hearing two tunes at the same time on different speakers. Broadly speaking, the mood on the nationalist side is upbeat. Unionists are more cautious and reserved, pointing to issues such as decommissioning which still give them cause for concern.

However, both sides agree that the parties are at last getting down to the real issues. A nationalist source rejected the word "breakthrough" but conceded there was emerging common ground.

By and large, the public has been very patient throughout the whole exercise. There is a genuine appetite on both sides of the divide in Northern Ireland to see permanent and lasting peace, but as always "the devil is in the detail".

Credibility problems will begin to arise for the talks if there is not some evidence of progress in the near future. The current positive mood will not last if the outline of a possible settlement fails to emerge fairly soon.

Senior unionist sources said the talks participants had begun to get down to serious work. Some of the bilaterals during the past fortnight had started to address fundamental issues. But whatever about identifying the difficulties on Strand Two, for example, there certainly wasn't agreement on how to resolve them.

One of the first issues that had to be decided was "based on the principle of consent, the reality that Northern Ireland will remain part of the United Kingdom". Unionists were "very, very disappointed" at the lack of progress on decommissioning and this would be reflected at next week's "review plenary". Unionists would also be seeking a general recognition that, whatever the details of any outcome to the talks, Northern Ireland remained in the United Kingdom firmly and without equivocation.

The UUP had not seen the detail of the SDLP's proposals on North-South relations but there was "a long way to go" on this issue. "We will not be agreeing to all-Ireland bodies with executive powers," unionist sources said.

It was originally intended that the review plenary, with all the parties sitting around the table, would run through Monday, Tuesday and Wednesday. Now Monday is to be devoted to preparing for the plenary proper, which will not commence until the next day, probably at 1 p.m.

The chairman, Senator George Mitchell, has asked the parties for submissions indicating the key points that need clarification. The hope is that the plenary will agree a timetable for discussion of these topics. It might be decided to set up subcommittees on different subjects, with two members from each delegation instead of the usual five; not so much "small is beautiful" as "small might be more productive". Obviously a sub-group dealing with North-South relations would attract most attention.

Last week's relatively successful meeting between the Taoiseach, Mr Ahern, and the UUP leader, Mr David Trimble, has given fresh impetus to the Stormont discussions. Nationalist sources said the meeting indicated that the UUP was at last "willing to engage, and engage seriously", although they cautioned that this could be a "false dawn".

There seems to be a fairly benign attitude from moderate nationalists to the unionist notion of a "Council of the British Isles" although the preferred title might be a "Council of the Isles" or a "British-Irish Council". This would include representatives of both parts of this island as well as London and the new devolved administrations in Edinburgh and Cardiff. There might also be a parliamentary tier.

It is not clear what powers such a council might have, but it could well be part of what Mr David Andrews calls the "institutional architecture" emerging from the talks. It could also help the unionists to swallow some of the less palatable aspects of a North-South body.

There is an urgency now, given that the talks will probably break for Christmas in about three weeks. If the parties are to keep to the original timetable, then there will be only three months from early January to tie up an agreement which would be put to referendums North and South in May.

Although significant progress has been made on Strand One (the internal arrangements for Northern Ireland), highly contentious issues remain, such as the composition and acceptability of the police force. Discussion on these issues would have to continue even after a settlement.

On strand two, the SDLP proposal that the implementation of joint decisions by a North-South body would be a matter for individual jurisdictions, may be the basis for solving the Rubik's Cube of the talks: how to give solid recognition to nationalist identity without alarming unionist neighbours.

Without a solid North-South body, voters in the Republic may not be willing to modify Articles Two and Three of the Constitution, expressing Irish unity as an aspiration rather than an imperative. Nationalists, North and South, will also have to be convinced that there is no going back to the old days of discrimination under the Stormont regime.

Nationalists would also wish to see corresponding changes in the Government of Ireland Act which partitioned the island in 1920. "It's going to be a hard sell," sources in the Dublin administration said.

Given that the Democratic Unionists and the UK Unionists are bound to oppose any referendum proposal, the attitude of republicans could be crucial. In a statement this week, the Sinn Fein chairman, Mr Mitchel McLaughlin, said his party hoped the talks "can provide the new constitutional and political arrangements which will move us away from the failed politics of partition and division". Since the unionists are seeking the further consolidation of partition, Senator Mitchell has his work cut out. Nevertheless, as a source in the SDLP put it, "Next week's review plenary allows the opportunity for things to move up a further notch."