BORIS JOHNSON will make his first visit to Scotland tomorrow as Prime Minister amid an internal party backlash over his Ministerial appointments.

He is expected to meet Scottish Tory leader Ruth Davidson - one of his fiercest internal critics - and may also hold talks with First Minister Nicola Sturgeon.

Johnson became Prime Minister last week, but his decisions relating to Scotland have already caused consternation within the party north of the border.

The new PM fired David Mundell - a Davidson ally - as Scottish Secretary and appointed English MP Robin Walker to a junior role, snubbing the rest of the Scottish Tory group at Westminster.

Sources believe Johnson and Davidson will meet in Scotland tomorrow as part of a trip that will see the Prime Minister promote the Union.

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Meanwhile, Walker has said he will work to ensure that the Union thrives "through Brexit and beyond".

Walker, who has been the MP for Worcester since 2010, was named as parliamentary under-secretary of state at the Scotland Office on Friday.

He replaces Ian Duncan, who is moving to the Department of Business, Energy and Industrial Strategy.

As well as working in the Scotland Office, Walker will also work in the Northern Ireland Office.

On Twitter, he wrote: "A huge honour to be made Minister for the union working with @BorisJohnson @ScotSecofState & @NIOgov - our precious union deserves to thrive through brexit & beyond.

"I will work with colleagues all across the UK to ensure that it does."

Walker, who was educated at St Paul's School in London and at Balliol College, Oxford, will work with Alister Jack at the Scotland Office after he was appointed as Secretary of State for Scotland earlier this week.

Jack was appointed by Prime Minister Boris Johnson as a replacement for Mundell, who had held the job since 2015 under David Cameron.

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SNP MP Tommy Sheppard said the appointment was further evidence of Scotland being ignored by Westminster.

He said: "This is another humiliating snub for Ruth Davidson, whose influence is rapidly ebbing away and who must be concerned a leadership challenge will be in sight.

"It is staggering that Boris Johnson thought a Brexiteer Tory MP for Worcester would be a better appointment to the Scotland Office than any of the Scottish Tories - revealing their lack of talent.

"Yet again, Scotland is being ignored by Westminster, and Robin Walker's appointment demonstrates how little regard the Tory government has for Scotland's views and interests."

In another development, Johnson has pledged a £3.6 billion boost for left behind towns as he sought to shift the political spotlight from Brexit to the domestic agenda.

Johnson also used a keynote address in Manchester to pledge funding for a new rail link between the city and Leeds, as well as a boost for broadband connectivity and extra resources for crime-fighting.

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The emphasis on the domestic agenda continued to fuel speculation the PM is keeping his options open for a snap general election, despite his strong denials.

The PM said: "We are going now to have a £3.6 billion Towns' Fund supporting an initial 100 towns, so that they will get the improved transport and the improved broadband connectivity that they need."