Ruth Davidson’s departure from frontline politics is likely to have significant ramifications not only for her party but also for the future of the union.

The 40-year-old spearheaded a Conservative revival in Scotland and successfully detoxified a party that had languished in the electoral doldrums for decades. She had been expected to play a key role in any future pro-union campaign, with the SNP still aiming to hold a second independence referendum by the end of 2020.

Scottish Tories acknowledge that the majority of their recent success is thanks to Davidson’s magnetic personal appeal (she is one of two serving Scottish politicians immediately recognised by their first name, the other being the first minister, Nicola Sturgeon) as well as her ability to galvanise the pro-union vote.

Her resignation raises questions about the punishing toll that political office can take on family life. Davidson’s voice cracked momentarily during her leaving statement as she described the impact of her position on her loved ones. “I fear that having tried to be a good leader over the years, I have proved a poor daughter, sister, partner and friend,” she said.

She leaves the party in a stronger position than it has ever been since devolution, but without Davidson at the helm there are serious doubts about whether the Scottish Conservatives can hold on to their 13 Westminster MPs or, indeed, second place at Holyrood.

Throughout this summer’s Westminster leadership campaign, the Scottish party was painfully aware of the impact that a Boris Johnson premiership was likely to have on its standing with voters, bolstering Scottish nationalist arguments that Westminster represents only a wealthy southern elite.

Its electoral successes were a direct result of Davidson’s comprehensive remodelling of the party, changing policy emphasis and bringing in talented individuals who did not fit the traditional Tory mould. Scottish Conservatives are well aware of the challenge they face to explain Johnson’s Brexit policy to remain-minded Scots on the doorstep.

Davidson allies were sounding understandably stalwart on Wednesday. The party’s constitution spokesperson, Adam Tomkins, who is tipped as a potential successor, said: “Ruth has been an extraordinary leader but this is not a one-woman band. She assembled a very talented bunch of people around her.”

The goal for the next leader will be to harness and build on Davidson’s broad appeal. While she garnered headlines as a state-educated, lesbian leader from a working-class background, she also appealed to many more traditional Tory voters as a committed Christian, former army reservist and able opponent of Sturgeon across the Holyrood chamber.

Nonetheless, there is an understanding that, having transformed itself into “the Ruth Davidson party”, another similar evolution has been forced upon it by Davidson’s decision.

At the heart of this must be the forging of a new relationship with the Westminster leadership, which is likely to continue to present difficulties given Scottish voters’ preference to remain in the EU, as laid bare in May’s European election results. Most of those likely to be in the running to succeed Davidson also backed remain.

As colleagues absorb the news, the consensus is that Davidson will be a uniquely hard act to follow.