All political parties require mythologies, historical provenance that somehow lends credence to their past, present and - most importantly - their future.

In early 21st-century Scotland the central feature of these mythologies is devolution, i.e. where each party stood, and indeed stands, in relation to the century-plus campaign for a devolved Scottish Parliament.

Inevitably this history gets rewritten. The SNP, for example, has reinvented itself as the party that championed devolution in the 1980s and 90s, compelling reluctant Labourites to deliver devolution through a combination of electoral virility and constitutional logic.

The annus horribilus of 1979 is constantly invoked as proof that Labour and the Tories can't be trusted, that all promises of devolution will be reneged on. It matters not that Labour eventually delivered a Scottish Parliament in 1999, and thereafter helped deliver more powers; 1979 drowns everything else out.

Similarly the Liberal Democrats have invented a century-long commitment to federalism, when in fact it was only in 1968 that Jeremy Thorpe nudged the old Liberal Party into supporting a formal federation rather than 'Home Rule all Round'.

Finally, the Conservatives suffer the most from their history despite having established the institutional and administrative basis without which legislative devolution would have been much harder. But they were duplicitous - or rather Lord Home was - in 1979, so they sit beyond the pale.

The SNP's rebranding as a party of devolution is curious, for until the summer of 1997 'Scotland's Party', still stung by the events of 1979, didn't support devolutionary halfway houses. While Labour and the Liberals co-operated via the Scottish Constitutional Convention, the SNP, as Johann Lamont put it on Saturday, 'were never on the home rule journey'. In fact, Salmond rubbished the Convention and sneered that Labour 'couldn't deliver a pizza, let alone a Parliament'.

Only in the wake of Tony Blair's first landslide did the SNP bow to the inevitable and accept devolution, subsequently posing as its guardian while Labour was depicted as hostile. As Lamont rightly pointed out on Friday, 'the SNP try to rewrite our history', although Labour - by and large - has let them.

Thus over the past few days Labour has been trying, as MSP Drew Smith put it, 'to reclaim devolution as the real alternative to separation'. This necessarily involves rewriting its own history, including the claim that devolution 'has been at the heart of Scottish Labour's agenda for 126 years'.

A new 'Red Paper' underlines this with pictures of Keir Hardie, Donald Dewar, Gordon Brown et al alongside the (decidedly Nationalist) banner 'TOGETHER WE BUILT A NATION'. After citing 1929, when Labour pledged legislative assemblies for England, Scotland and Wales, it then skirts over the rest of the inter-war and post-war period before name-checking John P Mackintosh and his 'influential' 1966 book The Devolution of Power.

But this devolutionary timeline takes several historical liberties. Not only did Labour's Home Rule pledge lapse in the 1930s and 40s but was formally abandoned in the mid-1950s. As for Mackintosh, his campaign for devolution was regarded with suspicion by the party mainstream, particularly the powerful Willie Ross, although there were honourable exceptions such as Donald Dewar.

Unveiling the Red Paper to the media on Friday afternoon, Scottish Labour's deputy leader Anas Sarwar, almost as an aside, said it had 'never been a party of nationalism' (while on Saturday Lamont said 'we will not wear nationalist clothes'), which again isn't quite true. During the Thatcher era Labour became a small 'n' nationalist party, pushing devolution, the 'no-mandate' argument against the 'anti-Scottish' Tories, and so on.

But then devolution has made all Scotland's parties, even the Conservatives, Nationalist to a degree; without wearing some nationalist clothes, they'd flounder. At conference Johann Lamont also jokingly referred to 'devo-Marx', an apt reference given Karl's observation that politicians conjure 'up the spirits of the past... and borrow from them names, battle cries and costumes'.

Thus the Red Paper pinches the term 'common weal' from Alex Salmond, UK Labour leader Ed Miliband referred to 'Britain's lost leader, Scotland's lost leader' John Smith, while other delegates name-checked Tom Johnston, John Wheatley and Jennie Lee. There was the usual misquoting of Donald Dewar about devolution being a 'process and not an event' (it was Ron Davies) but no mention of Tony Blair, who actually delivered devolution (against his political instincts).

The right-wing press, of course, emphasised the party's 'lurch' to the Left at this conference, although it's more of a throwback to the twilight years of New Labour with the restoration of the 10p and 50p income tax rates. Pensions spokesman Gregg McClymont, meanwhile, justified the devolution commission's tax power proposals (which can be moved up not down) on the basis that greater flexibility might result in 'a destructive race to the bottom on tax'.

This argument rested on another rewriting of history, that somehow Labour has never been a tax-cutting party, but as Chancellor Gordon Brown reduced the basic rate to 20p (in 1976 it was 35p) and also Corporation Tax from 33% (pre-1997) to 28% a decade later. So what Labour is saying is that other parties shouldn't be allowed to use Holyrood's tax powers to engage in a 'race to the bottom' but if Labour chooses to do so (having done so in the past), then that's a different matter.

Not only is contriving tax powers to prevent tax cuts Labour deems unacceptable fundamentally undemocratic, it's hardly compatible with the party having equipped the Scottish Parliament with tax-varying powers (however academic) in 1999. The logic of the 'race to the bottom' rationale is depriving Holyrood of any fiscal levers at all, which might be intellectually coherent but would hardly be politically deliverable.

Lamont said the devolution proposals were 'an act of faith with the Scottish people we can't go back on after the referendum', and so they should be, but while the prospect of an honest debate about income tax is to be welcomed, surely it would have been all the more effective had the tax proposals not been so contrived?

Nevertheless, Scottish Labour's attempt to nudge the debate back on to non-constitutional territory is a positive development. As MSP Jenny Marra observed at a fringe meeting, 'the debate about powers comes in the absence of ideas'. Those ideas are still a work in progress with Labour's 'moral economy' being - like the SNP's 'progressive' agenda - largely rhetorical. 'Equality is not a soundbite,' states the Red Paper, 'it drives our politics', but we await the proof in the pudding.

Victors, of course, usually write their own history, which explains the SNP's prowess since 2007. The language of priorities, according to Nye Bevan, is the religion of socialism, so it would be a shame if politics in Scotland, as in the Irish Republic, simply became a historical contest between who was right in 1979, 1999 and - of course - 2014.