Last week, Dr Vince Cable signed off on a Coalition spending review that had the explicit intention of eradicating 144,000 public sector jobs.

This week, he turns up in Glasgow to suggest a vote for independence will "destabilise enterprise and potentially put jobs at risk". Those will be the jobs left when George Osborne is done, presumably.

The Business Secretary came to Glasgow yesterday to brandish another Government "analysis" paper. This one is devoted to the "business and microeconomic framework". In one part of its summary the assertion is made that the "UK's shared business framework helps drive growth and competitiveness across the UK".

At a guess, this must be the growth whose absence Mr Cable bewails when he is not in Scotland advertising the benefits of the Union. Give him marks for gall, then, if nothing else. Week after week he points out, reasonably enough, that the single thing keeping the UK in the mire is a lack of economic growth. Then he comes north to warn us not to put non-existent growth "at risk".

In reality, Mr Cable did not visit Glasgow to talk of the Union's benefits. Better Together have all but given up on the fabled "positive campaign". Instead, we are to be given a daily dose of dismal from now until the referendum. You can almost picture Ukania's finest minds straining to concentrate of a morning while they struggle to come up with fresh horrors.

What have they missed? Mobile phones, pensions, postal services, transport, currency, passports, defence, banking, the BBC, pizza toppings – "Alistair, have we done pizza toppings yet?" – and anything that might ever matter to someone in Scotland. For laughs, the Yes campaign should ask Better Together to nominate what would be left in a post-independence wasteland. At this rate, we'll have a couple of mud huts.

By those standards, Mr Cable's job is trickier than most. Nick Clegg, his nominal leader, has already had to deny that the No campaign would make the average funeral seem cheery. As we reported yesterday, the Deputy Prime Minister said: "We're being unremittingly open with people about what is at stake." Make a note of the date: that was Nick "unremittingly open" Clegg.

Inadvertently, however, he raises a point. Many people continue to say they want "more information" before making a choice in the referendum. So how on earth will they vote at the next British General Election? Given past experience, do they have any reliable "information" whatever on what Mr Clegg, David Cameron, Mr Osborne and Mr Cable are liable to get up to if re-elected?

Never mind. Here's Dr Vince to inform us thoroughly. The burden of his message is that an independent Scotland would be in an economic isolation tank if it cut itself off from the UK's single market. There would be costs, rules, regulations, barriers and tax complications. Anything that might make a business owner feel queasy would become inevitable the instant Scotland voted Yes.

One hates to spoil the Minister's reveries, but let me take him back a few months. It's January. Mr Cable is in the fair city of Dublin for an affair organised by the British Irish Chamber of Commerce. Mr Cameron has just promised his Eurosceptics their referendum. Mr Cable has another of his visions.

In this one, the possibility of Britain quitting the EU is "highly improbable". On the other hand, the Minister is obliged to admit that it is, as the Irish Times will report, a "scenario possibility". In that event, Mr Cable the seer foresees a "green wall" trade barrier across the island of Ireland. He does not fear for the republic, but for its northern neighbour. Even Tory EU chatter, Mr Cable says, "doesn't help them".

In fact, according to the Irish Times, the Business Secretary "acknowledged the issues surrounding the dominant public sector in the North, identifying trade with the Republic as the best way for the private sector to flourish". Trade with a struggling eurozone nation was a better bet, in Mr Cable's analysis, than what the UK had to offer.

And what of that "scenario possibility"? Say one thing for the Tory Eurosceptics and all the Ukip-voting English folk who give Mr Cameron such nightmares: they don't quit easily. In fact, they seem as boisterous as ever. As we also reported yesterday, Scotland's views don't trouble them in the slightest.

James Wharton, MP for Stockton South, whose Private Member's Bill to secure an EU referendum by 2017 comes up this week, made that much clear. "This is an issue that affects the country as a whole," he said. "While we do have a devolved government in Wales and Scotland, this is an issue of foreign affairs and sits still in Westminster, and rightly should." The Scots, in short, would just have to lump it.

So what was it that Mr Cable told the BBC? This: "The last thing firms need is a new set of rules and regulations, new costs on exports, a smaller labour market and less reliable support for innovation and knowledge transfer." Combine more than 100 Tory MPs, the Ukip vote and the trend in English opinion. Where does the real "referendum threat" lie if Scotland votes No?

But still, let's attempt one of those positive arguments that Better Together find so hard to summon. Mr Cable and his paper describe Scotland's relationship with the UK in glowing terms. How would we cope as an independent neighbour facing all those fearsome rules, regulations and barriers? Where is the information so many demand? Across the Irish Sea.

The republic, let's be honest, does not have its troubles to seek. Its crooked bankers brought the country to its knees and gave fair warning of how a small nation should certainly not behave where financiers are concerned. But start with the elementary point: Ireland has no desire to be embraced again by the UK. Trade is another matter.

In fact, independent Ireland is the UK's most important European trading partner. Mr Osborne never tires of making the point. According to the Central Statistics Office in Dublin, Britain accounted for 15% of Irish exports in goods in 2012 (23.5% of exports if services are included) and 31% of its imports. Ireland is the UK's fifth most important market, representing 7.5% of our exports.

So when the Business Secretary visits Dublin, does he spend time talking gloomily of rules, regulations and barriers, or suggest that the Irish would be better off returning to a Union with Britain? I think not. Equally, though Ireland is in a bad way still, its statistics office does have one interesting fact to report in the matter of trade, Mr Cable's specialist subject.

Last year, the value of Irish exports topped 92 billion euros, a 1% increase on 2011. The cost of imports also increased slightly, to just over 49bn euros. I'll save you from looking for the pocket calculator. In 2012, the Republic of Ireland ran a trade surplus of 42.98bn euros. At the risk of labouring a familiar point, the Irish, as yet, have no oil of their own.

Better Together are welcome to the information. It's precious stuff, apparently, but always worth spreading around. They could start by sparing a little for Mr Cable.