JIM SILLAR'S words at his late wife's memorial service last month still pack a punch.

Calling on both sides in the constitutional debate to conduct themselves "the Margo MacDonald way", ie recognising "you are dealing with opponents not enemies, not with ogres but with fellow human beings" then, Margo's argument ran, the division would "be much easier to heal".

Sitting in the front row was the First Minister, with whom Mr Sillars had traded much invective over the years, and I remember being struck just hours later when an SNP press release - quoting Alex Salmond at length - popped into my inbox.

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Ed Miliband, visiting Glasgow that afternoon, had - according to the SNP leader - "zero credibility", led a party which had "abandoned its principles" and was heading to a repeat of the 2011 Holyrood election which had been an "unmitigated disaster for him and his party".

Indeed, Mr Salmond has always delighted in launching deeply personal attacks on his political opponents, something captured by the former Times sketch writer Matthew Parris who wrote, in the single best description of the First Minister, that he "combines an open countenance with an instinct for the low blow".

Just a few days ago the Prime Minister was added to a long list of figures to be attacked. David Cameron, said Mr Salmond, personified "everything that's wrong with politics in this country". Scotland, he added, was a country that had never and would never elect "people like him" to "govern us".

Now all is fair in love and referendums, but just hours later the First Minister was telling BBC Scotland the Yes campaign was "absolutely in thrall" to a "positive approach" in the referendum campaign and that, if anything, campaigning for independence had made him "accentuate the positive" even more; just not, it seems, in relation to Messrs Miliband and Cameron (and several others).

Salmond also operates on the basis that good lines bear repeating, over and over. Thus the Prime Minister's recent promise to legislate within the first year of the next Parliament (assuming he's still in office) for more powers was dismissed on the basis that another Tory toff, Lord Home, had made a similar pledge in 1979.

The SNP even circulated two Herald front pages to underline the point: one from 1979 screamed "No vote will not kill devolution, pledges Thatcher" while the other, from a couple of days ago, carried the similar message: "Cameron promises more powers if Scots vote No". "Let's not let history repeat itself," warned a party blurb, "the only way for Scotland to control Scotland's future is with a Yes vote."

This channelled Marx, who famously argued that history repeats itself first as tragedy then as farce, but although it is certainly the case that Mrs Thatcher, Lord Home et al were politically dishonest 35 years ago, it does not follow the same is true in 2014. The former Prime Minister, of course, remains a convenient bogeywoman for the Nationalists, but few Scots remember Lord Home or his comments during the 1979 devolution campaign.

The idea his intervention somehow killed devolution is risible. In 1979 a majority voted for a Scottish Assembly. What prevented it was the 40% caveat inserted by rebellious Labour MPs and, ironically, when James Callaghan's government tried to find a way through the resulting impasse, it was brought down by an unholy alliance of the Conservatives, Liberals and SNP via a motion of no-confidence.

Furthermore, anyone who'd been paying attention to Tory policy since 1975 would have known full well what its view of devolution was. The 1979 Conservative manifesto, meanwhile, committed it only to "discussions about the future government of Scotland", discussions that took place after the election but came to nothing largely because - true to future form - the SNP refused to take part.

Much of that, of course, is inconvenient history, which explains why it's been energetically rewritten to present the SNP as consistent champions of devolution and Labour its main enemy. But given all that's happened in the past 35 years, constantly invoking the annus horribilis of 1979 is an astonishingly weak line of argument.

Indeed, the SNP sometimes gives the impression it regards the existence of a Scottish Parliament as an inconvenient barrier to deploying the same dusty old arguments it has been utilising since the 1970s. The hated Tories, it seems determined not to acknowledge, are not only now pro-devolution but have - as the Prime Minister said during his recent visit - a track record when it comes to delivering more powers to Holyrood, most recently in terms of discretionary housing payments.

In a speech today, Nick Clegg will also attempt to reclaim some history by arguing that devolution is "in our instincts", reminding his audience that Liberal Democrats worked with Labour and others in the Scottish Constitutional Convention, and worked again with Labour and the Conservatives on the Calman Commission. The SNP was absent, of course, from both processes.

Thus the strength of Salmond's historical analogy appears to rest upon both Home and Cameron being Old Etonians or, as he charmingly put it, "people like him", a rationale not only relentlessly negative, but illustrates the extent to which historical grievance informs a pro-independence narrative that at the same time claims to be not only positive but forward looking.

Last weekend's newspapers were dominated by another attempt to view the current debate through a 1970s prism, the Scottish Government having conveniently unearthed another memo by the former Scottish Office economist Gavin McCrone, this one urging Mr Callaghan's government to establish a North Sea oil fund for the whole UK, but giving "especial priority to Scotland".

It's now widely acknowledged that not doing so was a mistake, although again it does not flow from that sorry reality that all the revenue generated from oil since the late 1970s has somehow been "squandered" or poured "down the drain". Of course there is an argument that it ought to have been invested more wisely, but at the same time billions of pounds went on public spending and, contrary to mythology, infrastructure (the Docklands Light Railway, for example, regenerated London's East End). Sure, a lot also went on benefit payments, but again it's difficult to regard that as "wasted" money.

Meanwhile, the Scottish block grant continued to increase, almost doubling between the creation of the Scottish Parliament in 1999 and 2010, funding higher public spending north of the Border which by McCrone's calculations was almost equivalent to Scotland's geographical share of North Sea oil revenue, not, for obvious reasons, an observation the SNP is keen on quoting.

Instead his 40-year-old economic analysis is cloaked in the usual paraphernalia: routinely confidential Civil Service memos become "secret reports", as if the current Scottish Government is somehow an unqualified fan of transparency in everything it does. But then, in retrospect, it's quite revealing so much of the pro-independence case relies on two debating points, one 35 years and the other almost four decades old. Last time I checked the forthcoming referendum was taking place in 2014, not 1979.