The Salmond and Sturgeon show

Just before Nicola Sturgeon took over the SNP leadership in November, Alex Salmond told Newsweek that she has been his "apprentice". In 2004, she ruled herself out of running for the top job, preferring to be his US-style running mate, and serving as deputy leader and Deputy First Minister in a devolved administration. The pair work hand-in-glove and have achieved a remarkably smooth handover.

But, as leader and First Minister, Sturgeon has her own style, stressing co-operation where Salmond delighted in confrontation. Salmond boasts of "taking notes" at Holyrood on how other parties can manipulate a minority government and the SNP says it will abandon its previous convention of sitting out Westminster votes on laws that do not apply to Scotland.

The UK-wide parties feel threatened. For Labour, the problem is acute: the top brass cannot tell whether Sturgeon means to follow the path of disruption mapped out by her mentor. In recent days, Sturgeon has made it clear that a hung parliament on 8 May would put her on the first plane down to London to take personal charge of negotiations with Labour leader Ed Miliband. "Even if the Tories are the largest party," Sturgeon says, "if there is an anti-Tory majority, yes, we would offer to work with Labour to stop the Tories getting back into Downing Street."

Both Labour and the SNP have ruled out a coalition and each day brings firmer denials from Miliband that he will do any deal with Sturgeon. Salmond, still a divisive figure, will be in the House of Commons if he wins the Gordon seat from the Liberal Democrats, and the Conservative attack ads claim he, not Sturgeon, will be "pulling the strings".

In an otherwise lacklustre campaign, and eight months after the referendum, Scotland is still generating the excitement. Sturgeon, who shone in televised debates, has become a superstar, stepping out from behind Salmond's shadow. The only female major player now has a personal following even outside Scotland. Left-wing voters are heard to regret the fact that the SNP stands no candidates south of the border. The question is, has she left her mentor behind, or is Salmond really the power behind the Queen of Scots' throne?