CASTING my mind back to early Medieval times, I recall my journalism tutor who advised me that the principal requirement for our trade was “rat-like cunning.”

Not sure I entirely agree but, either way, it is a transferable skill, easily adopted by the aspiring politician.

The would-be tribune of the people needs to be both sharp and smooth. A smidgeon of intellect helps, as does charisma.

All that – and good fortune. Right now, the contenders to lead the SNP are completely bereft in that department.

This entire contest is beset with mismatches. Number one arises from the UK Budget. Yes, Scottish Ministers can argue that successive Chancellors have pursued the wrong path, that they would act differently under independence.

Read more by Brian Taylor: Can the SNP survive this calamity of a leadership contest?

Folk just hear Jeremy Hunt announcing support for child care. Plainly exasperated, Nicola Sturgeon points out that Scotland’s package of support is already superior – and that the deferred plans for England are targeted, not universal.

Eventually, that argument should get through. But, right now, mid contest, the three contenders face questions which arise, not from their own campaign, but from external issues.

However, there are internal policy stumbles pursuing them too. Gender recognition – but also the economy.

All proclaim support, in principle, for the bottle deposit return scheme. All plan to finesse it: Humza Yousaf by exempting small firms, Kate Forbes and Ash Regan by postponing implementation.

Beyond that, there is the consultation on banning alcohol advertising. If fully implemented, that would, arguably, damage our whisky industry, a key employer and income-earner.

I have far too much respect for basic arithmetic to be a gambler. But I would wager that whoever wins the SNP leadership will dump or severely limit that idea. The trade already has enough gloom from the Chancellor’s ten per cent hike in duty.

The Herald: SNP badgesSNP badges (Image: free)

Right now, though, mid campaign, that issue is out there. Along with a health crisis, education worries – and our seeming incapacity to complete two ferries on an estuary which once supplied the world with ships.

Then there are other mismatches in this contest which resembles a quandary as much as a choice.

It would seem that Humza Yousaf is in the lead among party members. You know, the ones – now rather fewer in number – who will actually cast a vote.

But some surveys have suggested that Kate Forbes has a broader appeal, beyond the SNP.

She says that means she is capable of persuading No voters to convert to Yes. Sceptics say she puts off nationalists with her moral views.

Then the issue of relations with the Greens. Mr Yousaf would retain the pact. Ms Forbes and Ms Regan pose some questions.

There is economic strategy. Both Ms Forbes and Mr Yousaf cited “eradicating poverty” as their key aim. But they differ as to how.

Read more by Brian TaylorNew SNP leader will need to pursue a new direction

Kate Forbes favours enterprise and economic growth, vigorously denying any “lurch to the right”.

Humza Yousaf talks of a well-being economy – by which he presumably means one which measures redistribution and relative poverty, rather than simply GDP.

His big idea? Expanding state-funded child care to allow more people, chiefly women, back into the labour market. As he forecast, an idea now adopted by the Treasury, albeit in limited form.

Plus independence. All three candidates, of course, stress its vital importance. Ironically, this is the biggest mismatch of all.

Why so? Because the more they underline their desire for independence, the more we recall that it is not solely in their hands.

Independence is not like a campaign pledge on, say, education. Such a devolved pledge will either be redeemed or abandoned, dependent on the success or otherwise of the government led by the new First Minister.

Independence is different. It affects the wider United Kingdom. The constitution of the UK is explicitly reserved to Westminster in the 1998 Scotland Act. It is Westminster’s call as to whether a further referendum will be held, and when.

This week I asked each of the contenders to specify, precisely, how they envisaged attaining independence.

The most detailed answer came from Ash Regan. She proposes an independence convention, beyond the SNP, backed by a civil service commission to tackle policy issues.

She then argues that a popular majority for pro-independence parties at any subsequent Westminster or Holyrood election would constitute, of itself, a mandate to open negotiations with the UK Government as to “Scotland’s withdrawal from the UK.”

Further, she says there is “no possibility of the UK Government not agreeing”. She cites the countries which withdrew from the Empire, after resistance. And adds that she has a Master of Science degree in Development Management, in the study of how countries develop, alongside a BA in International Relations.

Her rivals are less sanguine about the path to independence – or perhaps alert to the turmoil and bloodshed which frequently preceded those exits from Empire.

Kate Forbes says she will focus upon building support for independence, rather than upon process. She says her pitch is “persuading No voters”.

Humza Yousaf matches that aim of a “sustained majority for independence” – by “inspiring people across Scotland with a positive, progressive vision of what the powers of independence can achieve.”

Now, Ms Regan would insist that her “voter empowerment mechanism” differs substantially from the approach of her rivals.

I hope she will forgive me if I dissent, ever so gently. She can disavow the role of Westminster with memories of Empire – but it still amounts, largely, to wish fulfilment, particularly as Scotland is an intrinsic component of the UK, rather than a colony.

It strikes me that all three face that mega-mismatch I mentioned earlier.

Their electorate, right now, comprises those 72,000 SNP activists who have stuck with the party. They want independence yesterday. They want an upbeat narrative.

Equally, the contenders know that neither Alex Salmond (even with an overall Holyrood majority) nor Nicola Sturgeon (with her intellectual and political clout) contrived to persuade sufficient Scots, nor to surmount the blockage of Westminster.

In essence, all three contenders seek to build upon devolved powers – to exemplify, cajole and inspire.

Challenged this week, the current First Minister said Scotland’s future was, ultimately, in the hands of the people. As it should be.