CHEER up, it might never happen. It is a favourite phrase of women everywhere. You might have thought it was on the way out, arm in arm with wolf whistling and smoking beagles, but instead it is the basis for a summer bout between the Conservatives and the SNP, a fight to see who can be the most optimistic about Scotland. Let joy be unconfined.

In the slightly red corner is Andrew Wilson, head of the SNP’s growth commission. The former MSP will tomorrow publish the long awaited reboot of his party’s economic case for independence.

Entitled “Scotland – the new case for optimism”, the report bills itself as a strategy for “inter-generational economic renaissance”, a phrase sure to go down as smoothly in the common parlance as Ed Balls’ “post-neoclassical endogenous growth theory”.

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First Minister and SNP leader Nicola Sturgeon will then take this report and hit the road for a series of “national assemblies”. In what is the political equivalent of sending the kids out to the back garden with a ball, this will allow party members to burn off some of the pent up energy they have been amassing while their leader has been swithering over another independence referendum.

In the blue corner is Ruth Davidson, leader of the Scottish Conservatives. Rather an unevenly matched bout this one as Ms Davidson is a one woman tank division of cheeriness, known for crushing everything underfoot in her determination to “crack on” and get things done. The latest obstacle in her sights is, rather daringly, her own party.

Let loose in London for the launch of a new think tank (called, what else, “Onward”), Ms Davidson accused the Conservatives of looking “a bit dour” and coming across as hectoring and authoritarian. The party had to learn to be more joyful, she advised, as it had in Scotland.

Environment Secretary Michael Gove was so tickled by this he joined in, telling the audience that the party in the past had sometimes seemed “censorious and finger-wagging, pessimistic and unhappy”. He then said spending time on a platform with Ms Davidson was like being “Ike to Tina Turner, or Sonny to Cher”. Or Basil to Sybil Fawlty. Or Tom to Jerry. Insert own unsuitable comparison here.

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Given the gauntlet thrown down by Ms Davidson, Downing Street was forced to reject the accusations of joylessness. You can imagine how delighted the PM was about that. It will have helped Ms Davidson’s case that the boss has form herself in calling the Tory ranks to task, but it took a long time for hackles to go down after Theresa May’s “nasty party” gibe.

One does not imagine Ms Davidson being in the dog house for long, if at all, because she is one of the party’s two licensed jesters, the Scrappy-Doo to Boris’s Scooby-Doo. As with Boris, the jokiness cloaks a wholly serious ambition, one the SNP, and Labour, are failing to get a handle on. How is it that the leader of a party that came to be almost universally despised in Scotland can so often be found running rings round a party that is in government, and one that was in government?

There is no real need to explain why Scottish Labour has been unable to halt Ms Davidson’s electoral progress. It is Scottish Labour; for the past ten years it has been about as much use as a patio on a submarine. More of a mystery is why the SNP are so often knocked on to the back foot when Ms D goes on the offensive.

Now, there is always the possibility that the leader of the Scottish Tories is some unparalleled political genius of the post war age, a strategist on a par with Cicero, a thinker to make Plato quake. To her credit, I think Ms Davidson would be among the first to guffaw at such notions. But still, why does her star keep rising while those of others fall? What is the truth of Ruth’s appeal?

Perhaps her biggest asset is the ability to put a distance between herself and her still toxic party. She is as up to her neck in austerity, benefits sanctions, limits on child tax credits and the accompanying “rape clause”, etc, as the rest of her party yet somehow the charges never stick. She is seen as so progressive, indeed, that Lord Alistair Darling, at the same event with her on Monday, was able to say, only half-jokingly, “I still wonder why you are a Tory.”

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Next, she keeps her message simple and the mood music that surrounds her jaunty. Monday’s speech was a perfect example. She wanted more Union in the Union, to spread the benefits around and give Scots the feeling that they had more of a stake in staying together. Why not a UK-wide World Cup bid, she ventured? Why doesn’t the British Museum send some of its treasures north? It is the privilege of opposition to agree to everything and commit to nothing, but even so, where was the counterattack? Where was the picking apart of her policies? More to the point, where are her policies?

Where Ms Davidson is at her most effective is in defining herself in contrast to her opponents. It used to be thought that her old leader, David Cameron, was the heir to Blair but Ms Davidson has been on that course too and passed with flying colours. Like early Blair faced with the too long in power Tories, she knows all the right notes to strike. She speaks of optimism, of sunniness, refreshing the party, appealing to all ages, being an antidote to the “politics of anger”. The only thing missing is a blast of circa 1997 “Things can only get better”. Ms Davidson takes the labels she wants, and leaves what is left in the box for her opponents. She is hard at work, so they are falling down on the day job. They are dour, so she is upbeat. A simple strategy, but one that can be difficult to counter once it takes a hold.

While it is easy to dismiss Ms Davidson’s call for more a little more joyfulness as so much piffle it should be remembered that no-one ever got far in politics, or much else, by appearing to be always on the defensive. SNP strategists should remember that voters are here for a long time, not a hard time, and strike a mood and pace accordingly. Otherwise it will be Ruth, and her alone, laughing all the way to more victories.