THE SNP's 2010 General Election campaign launch was a largely forgettable affair.

You'll not remember the clunky slogan: "More Nats means less cuts," or Alex Salmond's demand Scotland be included in the first phase of Britain's exciting new high-speed rail plans. "As the events of recent days have shown, the Scottish economy cannot rely on domestic air travel alone," he said, referring to the big story of the day, the transport-disrupting eruption of an Icelandic volcano, Eyjafjallajokull. You might vaguely recall his veiled backing for the LibDems down south (if only because Labour have let no-one forget it) but you are probably hazy on exactly why the SNP leader was so keen on seeing a hung parliament. It would be the only way, he argued, to force the UK parties to drop their opposition to an independence referendum.

How strange all that now sounds with the benefit of just four years' hindsight. Journalists present that April day were left with the impression the SNP, if not exactly sitting this one out, was keeping plenty in reserve for the following year's Holyrood election. The venue in Glasgow city centre was pokey, the manifesto booklet flimsy, the mood, well, a little flat. Mr Salmond's target - a powerful bloc of 20 Nationalist MPs holding the balance of power at Westminster - seemed like pie in the sky. The hacks were right on both counts, as things turned out.

The SNP's 2011 Holyrood campaign was unrecognisable from its low-key 2010 effort, as were the results. In the Westminster poll, the Nats won six seats, the number they held going into the election, and claimed a fraction under 20 per cent of the Scottish vote. Labour may have lost to the Conservatives across the UK but under Gordon Brown the party did well in Scotland, winning 41 out of 59 seats with a mighty 42 per cent share of the vote. You'll not need to be reminded how the parties' fortunes were so dramatically reversed in the Scottish Parliament contest a year later.

On Wednesday, David Cameron turned the Conservative conference in Birmingham into a pre-election rally, dangling a retail offer of tax cuts and promising a presidential battle between "me and the other guy". Don't get too hung-up on policies, it's Dave versus Ed for No 10. The vote in seven months' time will be very different from 2010. For a start, there is no chance the SNP will be sitting it out. This time, you sense the SNP would prefer a Conservative government at Westminster.

The Nationalists object sincerely to Mr Cameron's £25 billion austerity programme but his continued presence in Downing Street would serve their purpose. A second term of the Tories would reinforce their view Scotland and England are set on different political trajectories. Furthermore, it offers the prospect of an in/out referendum on the EU. If Scotland voted In while the rest of the UK voted Out in 2017, there are many who believe it would justify a re-run of the independence referendum. They have a big incentive to slash the number of Labour seats in Scotland.

The signs are looking good for the SNP. A YouGov poll conducted after the Prime Minister's speech put the Conservatives in the lead over Labour for the first time since March 2012, albeit by a narrow 35 per cent support to 34 per cent. In Scotland, pollster Panelbase put the SNP ahead of Labour in the race for Westminster seats. Support for the Nationalists was at 34 per cent, compared with 32 per cent for Labour and 18 per cent for Ruth Davidson's rejuvenated Conservatives. And that's before the SNP mobilises its army of new members - 50,000 of them - who have a first opportunity to campaign for the party. It's no wonder a good many Labour stalwarts privately fear the Nationalists will achieve their previous target of 20 seats this time around.

Labour has its work cut out, first to reconnect with core voters and secondly to present a convincing devolution package for Holyrood. In his conference speech, Mr Cameron tried to neutralise the threat posed by Nigel Farage when he told Tory waverers: "A vote for Ukip is a vote for Labour." Labour are sure to tell Scots voters: "A vote for the SNP is a vote for the Tories." It worked in 2010, when then-Scots leader Iain Gray parodied the SNP slogan as "more Nats mean Tory cuts". Labour cannot be so confident that same message will work as well next year.