So Scotland’s voters have turned up another surprise. Last year they voted for the SNP in sufficient numbers that the Nationalists were rewarded with an overall majority despite the use of a system of proportional representation. This year, rather than confirming the exuberance and confidence surrounding the nationalist cause, they stepped back, leaving the SNP barely ahead of Labour in terms of both votes and seats.

In truth it never seemed likely that the SNP would emulate last year’s remarkable success in full. That triumph was the product of a disastrous opposition campaign and an uninspiring Labour front bench that presented little challenge to an SNP ministerial team and leader that exuded charisma and confidence.

It was achieved too in a context, a Scottish parliamentary election, in which voters have always been relatively inclined to back the SNP.

Even a moderately competent Labour campaign this time around could be expected to bring a richer reward than twelve months ago.

Whether voters would prove as inclined to vote SNP in local elections that did not take place on the same day as a Holyrood contest was always a major unknown. Meanwhile as it happened, Labour’s current standing at Westminster provided the party north of the border with a potentially helpful following wind.

Moreover, it would be a mistake to belittle what the SNP did manage to achieve. Their (according to their own tally) 32.3 per cent of the Scotland-wide first preference vote represented the party’s highest ever share in a local election contest. The party outpolled Labour, albeit narrowly, in terms of local election votes for the first time ever. Thanks to the use of proportional representation, the Nationalists’ performance translated into a record number of council seats too. These are achievements that few would have imagined possible just a few short years ago.

Yet despite all these considerations, there is still a sense that the Nationalists ought to have done better. In setting the removal of Labour from Glasgow as the litmus test of its performance the SNP themselves certainly sent out a signal that they reckoned they could match last year’s success. Not all the (very limited number of) opinion polls published since the New Year agreed with that prognosis, but even the least favourable put the SNP at between four and six points ahead of Labour in Holyrood vote intentions. Meanwhile, in local government by-elections held during the past twelve months, SNP support was up on average since 2007 by twelve points, well above the four-point increase that emerged from the 3 May ballot boxes.

Above all, that 32.3 per cent of the first preference vote is no less than 13 points down on what the party achieved on the Holyrood constituency ballot twelve months ago. True, some of the difference is to be accounted for by the relative strength of Independents in local elections, but that cannot explain how a lead over Labour of 14 points should have diminished into one of just a single point now.

But all in all, even someone making a sober estimate of what the SNP might reasonably expect to achieve would probably have anticipated it would manage at least a four or five-point lead.

So, what might have gone ‘wrong’ for the SNP. The immediate political backdrop to the elections was of course not the most favourable one, as opponents leapt on Mr Salmond’s past association with Rupert Murdoch. Much of the criticism of the First Minister’s actions was laced with the benefit of hindsight, but nonetheless it may have helped puncture a little the impression of a man who always knows what is best for Scotland.

But behind that short-term embarrassment, there is perhaps a bigger question to be asked – just what is the SNP Government doing for Scotland that might make voters sit up and take notice? Despite having a parliamentary majority, the SNP’s legislative programme still looks remarkably thin, at least so far as distinctive headline-grabbing measures are concerned.

Beyond a recycled version of the Government’s minimum alcohol pricing legislation, there is little to catch the public eye. Legislation is of course not everything, but conveying to voters the impression of a government with drive and direction is certainly not made any easier by the absence of eye-catching parliamentary activity.

Of course there is one subject on which the SNP certainly has been active – the independence referendum. Indeed, now the local elections are over and the Scottish Government’s consultation draws to a close, we can doubtless anticipate that the debate about how the referendum should be conducted will soon come to life once more. Yet independence was not the issue that brought the SNP victory twelve months ago – support did not increase during the course of the campaign and around half of those who voted for the SNP did so despite not backing independence. In suggesting that victory for the party in Glasgow would be ‘a stepping stone to independence’, the SNP leader in the city, Alison Hunter, simply reminded voters of the one reason why they might want to draw back from supporting the SNP again.

In short, the SNP have perhaps been reminded by voters that twelve months ago they elected Mr Salmond and his colleagues above all to provide Scotland with competent and effective government. In England the Tories certainly were given a rude reminder on 3 May of how voters are ready and willing to punish governments that are thought to have failed the competence test. As the SNP tries to plan and plot its path towards victory in an independence referendum, it needs to remember that not only does it need a convincing vision of what an independent Scotland might look like in future, but also a persuasive narrative about what it is delivering for Scotland in the here and now.

John Curtice is Professor of Politics, Strathclyde University