The new leader of the Scottish Conservatives has said his party must earn the trust of people “looking for a positive and credible alternative for Scotland” in his first comments since his uncontested appointment.

Douglas Ross described becoming leader of the Scottish Tories as an “honour and privilege of a lifetime” after his appointment was confirmed at noon on Wednesday.

The Moray MP will take over from Jackson Carlaw after his resignation on Thursday, just six months after his election as leader.

Mr Ross is expected to seek a seat at the Holyrood election in 2021.

After his appointment, Mr Ross tweeted: “Becoming leader of the Scottish Conservatives today is the honour and privilege of a lifetime.

“Now our focus must turn to earning the trust of people looking for a positive and credible alternative for Scotland, and who want a fresh start for our country.

“I hope you’ll join us.”

Former leader Ruth Davidson has been asked to represent the party at First Minister’s Questions.

Ms Davidson has said she will step down from Holyrood next year to take up her a seat in the House of Lords.

In the first 30 days of his leadership, Mr Ross has said he will publish an economic plan for Scotland, effectively launching the Conservatives campaign for 2021.

He also said he would like more powers to be given to local authorities to combat what he said has been a “power grab” from the Scottish Government.

Previously an MSP between 2016 and 2017, Mr Ross represented the Highlands and Islands region before beating SNP depute leader Angus Robertson for the Moray seat at Westminster.

After being appointed a Scotland Office minister in December, Mr Ross resigned in May over senior adviser Dominic Cummings flouting government guidance by travelling to Durham and Barnard Castle during lockdown.

SNP depute leader Keith Brown said: “Douglas Ross is Boris Johnson’s man in Scotland.

“Westminster has launched a total takeover of the Scottish Tories and installed a Brexit-backing MP to act as a puppet for Downing Street.

“As his Westminster voting record proves, Mr Ross couldn’t be more out of touch with Scotland.

“His offensive comments on gypsy-travellers were appalling and he has rubber-stamped every damaging decision on an extreme Brexit, a power grab on the Scottish Parliament and deep austerity cuts to public services – despite the harm to our communities.”

He added: “With the threat of Brexit growing, senior Tory MSPs and advisers jumping ship and Baroness Davidson preparing to join the House of Lords, it is clear the Tories are the same old party with nothing to offer except selling Scotland out.

“Whatever else we’ve learned in this whole grubby coup, and whatever their bluster, senior Tories are now effectively conceding publicly what they have been saying privately for some time – they know there is going to be an independence referendum.

“Otherwise why bother changing leaders?”

Scottish Greens co-leader Patrick Harvie said: “Just months ago, the Scottish Tories were maintaining the pretence that they were something different from the extremist no-deal Brexiteers of the Boris Johnson camp.

“Today the instalment of Douglas Ross as their part-time, absentee leader without even asking their members confirms that there isn’t a hint of difference between them.

“It’s also clear that the Prime Minister thinks the entire Holyrood group is useless, having overlooked the lot of them to appoint a backbench MP as leader.”

He added: “Combined with the stand-in role of Ruth Davidson, who is only marking time at Holyrood till she gets her ermine and her unelected job for life, it’s all symbolic of Boris Johnson’s contempt for Scotland and our Parliament, and even for their own members.

“It’s not just internal democracy the Tory leadership have disdain for.

“They are clearly intent on pressing ahead with the power grab against Scotland, with new legislation planned to give themselves a veto over any decisions that don’t fit their failed free market ideology.

“If Mr Ross wants to earn a shred of credibility, his first act as leader should be to insist that plan is scrapped. But I won’t be holding my breath.”