THIS month's System Three poll for The Herald seems to suggest the political equivalent of the raising of Lazarus, with Labour projected to be the single largest party at Holyrood despite still trailing the SNP on both first and second ballot questions. It also shows the considerable difference that can be made to the overall make up of the Scottish Parliament by relatively small fluctuations in the vote.

Last month, a national swing analysis - applying the swing from one party to another since the 1997 General Election - gave Labour 46 seats and the SNP 56 seats. This month, the same type of analysis gives Labour 55 seats and the SNP 52 seats. This is a significant turn around in the projected result with the balance of power shifting back to Labour.

What is interesting is how this has been achieved on small, but consistent changes in the vote. On the first ballot question, Labour is up 3%, the SNP down 4%. On the second ballot question, the change is Labour up 4% and the SNP down 2%. Shifts of up to this magnitude in opinion polls of the type used by System Three could be explained away by sampling error. For analysts this causes a real headache as small changes between two closely matched parties can yield, as in this case, different results in the make up of the Parliament.

However, what is also important is an examination of the trend, which has showed on the single question measurement of support for a Scottish Parliament since the beginning of the year an SNP advance which peaked last month with an SNP lead of 14% over Labour. This month the SNP lead has been pegged back to 6%. There has been evidence over the past three months that any SNP advance was slowing. Today's figure suggests that it is possibly in reverse.

For Labour the news will be very welcome. Its own private polling, which Labour's spin doctors have kept close to their chests, has shown a brighter picture for Labour. System Three's results may support that message. A gloomy June and July ended with a bang with the appointment of Helen Liddell to a portfolio at the Scottish Office with enough room to allow a more active campaigning roll. System Three's fieldwork was carried out immediately after Tony Blair's reshuffle and may indicate some positive response to the changes.

The figures may also reflect a boost for Labour from the Comprehensive Spending Review and its commitment to boosting funding in key public services such as health and education. Concern over public services is one issue that has been high up the agenda of voters for a number of years. However, this interpretation must be tempered by the most recent ICM survey which put the SNP ahead of Labour for the first time and suggested that the public's response to the spending review was lukewarm at best.

Labour has, of course, attempted to stem the tide of the SNP's rise by altering key party personnel, of which the appointment of Gus Macdonald as Industry Minister was the latest instalment. This month's figures may be a sign that its strategy is paying off, at least in terms of coming back into contention at a time when next May's elections looked to be slipping away from it.

For Alex Salmond the news that our projection puts them in second place at Holyrood once again will come as a disappointment, but only a small one. The bare facts are that Labour's projected position as single largest party comes only on the basis of the advantage Labour possesses of the first past the post element of the electoral system. Here, Labour has 40% in this month's poll, with the SNP on 41%. Despite this lead, Labour gains 50 out of 73 constituency seats with the SNP only taking 17.

The SNP then will be happy at yet another poll that puts it ahead of Labour on both ballots. However, it will need to be concerned with the way in which Labour is now attacking its policies head on. The recent Labour calculation of 15p on income tax to pay for the SNP's programme is clearly an opening shot of a more aggressive campaign. However, the fact that Labour is turning to such tactics is in some sense good news for Alex Salmond. It clearly shows that Labour takes the SNP's threat to be real and therefore worthy of a response.

Labour may try to capitalise on this poll, but two facts remain which it must bear in mind. The SNP is still ahead, for one. However, more important than one month's poll findings is the likely trend up until next May. Most analysis of a second year in a Government term shows Government popularity and support fading rather than increasing. The mid term blues may end up turning a large proportion of Scotland yellow.

* Malcolm Dickson is Lecturer in Politics at the University of Strathclyde