When David Cameron arrives in Scotland today to champion the virtues and benefits of Scotland remaining in the United Kingdom let's hope no Nationalist questions his credentials or the right to make the case.

Mr Cameron's view on the Union represents the majority of the Scottish electorate in both the Holyrood and Westminster elections and,whether you like or loathe the Conservative Party and its policies, the Prime Minister should be a welcome visitor, not least because Ewen Cameron, his grandfather, was Scottish.

Roisin McLaren's intemperate intervention earlier this week, name checking David Cameron as "English" and a "toff Tory politician" was depressing and surely off-putting to potential visitors.

Many in Scotland's important tourist trade pride themselves on their hospitality and welcome so what does it say to the hundreds of thousands from around the world who will be looking forward to enjoying the exceptional cultural and golfing delights on offer in Scotland this summer?

Most of Scotland's visitors hail from England and they contribute hugely to Scotland's GDP. But the remarks of the president of the Scottish Nationalist Association student society at Edinburgh University are a stark reminder of the dark side of nationalism.

As well as being depressing and deplorable, this was ludicrous and laughable for, even in the unlikely event of Ms McLaren achieving her dream of breaking up the UK, Scotland would be left with its fair share of the characteristics she so despises in Mr Cameron. In advance of the Prime Minister's visit, Mr Salmond joined in the fray, albeit with a more subtle touch.

When he says "he [Mr Cameron] personifies everything that's wrong with the politics in this country at the present moment, where a Tory Prime Minister with minimal, negligible support in Scotland can command political authority over our country, a country which has never and will never elect people like him to govern us", what exactly does he mean?

Mr Salmond and Ms McLaren are perfectly within their rights to criticise Mr Cameron's policies. But discussing policy, particularly economic policy, does not feature in the Nationalists' lexicon. Rather, they accuse their opposition of negativity and scaremongering.

As employers, large and small, warn against the risks of splitting Scotland from the UK, the Better Together campaign has a moral as well as a political duty to spell out the risks. They too care about the future of Scotland. If they think independence will lead to a higher cost of living, job losses, cuts in public services or higher taxes and a risk to benefits, pensions and the economy they should say so.

Many Tory policies are anathema in Scotland and England but a major problem in Scotland is the lack of an ideological debate. If Mr Cameron needs a reminder that the Tories should raise their game in Scotland to give the electorate a proper, values-based choice, Nicola Sturgeon, the SNP's deputy leader, should have left him in no doubt.

According to Ms Sturgeon the race for one of the Scottish seats in next week's European elections is shaping into a straight fight between the SNP and Ukip.

For at least the past 25 years, constitutional issues have skewed the political debate while there has been a desperate need for any political energy to be expended on improving the economy and public services. To change the tenor of the debate in Scotland is another good reason for voting against separation.

Ms Sturgeon claims the SNP's manifesto plans to work with Brussels to secure jobs and investment, to stand up for our agriculture and fishing sectors and to advance Europe's social agenda, particularly when it comes to the living wage. It's a strange world when it's acceptable to look forward to working so closely with Brussels while tearing up a 307-year old Union between Scotland and the rest of the UK.

And as we remember John Smith's tragically premature death, we should recall that he was driven by a need to deliver social justice. The Scottish Parliament has all the levers it needs to do just that.