“Utter bullshit.” “Copper bottomed absolute crap.” That is how Scottish Tory MPs are describing the Sun’s suggestion that their leader, Ruth Davidson, is plotting to seek a peerage and join the cabinet before the next Holyrood election in 2021.

Davidson is said to have told friends that she is no longer wedded to her ambition of becoming Scotland’s first minister. Instead, she wants to return from maternity leave next year and “prove she can run something”, something in this case being a Whitehall ministry from the Lords as a “stop gap”.

She would then renounce her peerage and fight a Westminster seat somewhere at the next general election, before running for leader.

If that sounds impossibly convoluted and like something that Davidson would never do, that’s because it is. Her allies and colleagues have dismissed the story as nonsense, pointing out that Davidson, her MPs and MSPs have spent the past two days brainstorming its approach to the 2021 election.

But it does contain a germ of truth: namely that Davidson, one day, wants to come to Westminster.

Her allies in SW1 freely admit this. And what this story does, ridiculous though it is, is underline the difficulties that lie ahead as far as realising that ambition goes, as well as deeper problems for the Tories in Westminster and Edinburgh. First there is the question of timing. The next Tory leadership election will almost certainly be before the next Holyrood election in 2021, which Davidson is committed to fighting.

Some Tories wonder if there is any way she can fight the leadership election that comes after that without losing her sui generis appeal as a potential candidate, or, indeed, any way she can fight it full stop.

The known unknowns are close to innumerable: if she manages to win in 2021, does she serve a full term? Does she fight the next Holyrood election? Does she have the same cachet as a leadership candidate if she loses in 2021? Where does she stand? When does the next Tory leadership but one even happen? Who are the other candidates?

Those questions, however, are distinct from the much simpler one of whether Davidson can or will come to Westminster as an MP. The answer to that is almost certainly a straightforward yes, as my colleague Chris Deerin has written before. But that itself poses problems for the Scottish Tories, whose distribution of talent is skewed towards Westminster anyway. Davidson’s departure for Westminster could well decapitate the party at Holyrood. Without her as saleswoman, can it continue its remarkable rise?

The six months Davidson will soon spend on maternity leave will give us a hint of the answer to that question. For the Tories nationally, meanwhile, the frequent and increasingly ludicrous talk of her arriving deus ex machina to save them reflects the thinness of the field of would-be leaders and its deep anxieties about the next election. A party pining for a prince across the water is never a healthy one. Just ask Labour, and David Miliband.