Devolution is not a “temporary stepping stone” on the way to Scottish independence, Theresa May’s de facto deputy will insist.

Cabinet Office minister David Lidington will use a speech in Edinburgh to stress that the Conservative government is “committed to devolution for the long run”.

And while Scottish Government ministers have complained about the relationship between Holyrood and Westminster, he will argue the differing views of ministers north and south of the border “have not prevented us from working together”.

The senior Conservative minister is in Edinburgh to speak at an event to mark the 20th anniversary of the establishment of the Scottish Parliament, which has been organised by the Law Society of Scotland.

First Minister Nicola Sturgeon is also due to address the conference.

Cabinet Office minister David Lidington (Stefan Rousseau/PA)

Mr Lidington will use his contribution to “celebrate the achievements of the devolved parliaments” and how “Scotland’s two governments can work together to deliver for citizens”.

He will tell the audience: “The UK Government is clear. Our vision for the nations of the United Kingdom is of strong devolved parliaments within a strong United Kingdom.

“Not as a half-in-half-out compromise. Or something to tolerate reluctantly. Or a temporary stepping stone to a different constitutional future. But as the settled state. Because devolution is not something that sits in opposition to being a unionist. It goes hand in hand with it.”

With Holyrood’s powers having been extended, Mr Lidington will insist the UK Government has acted to “support devolved governments to evolve and to champion them as the best model for the nations of the UK”.

He will continue: “We supported the Smith Commission and took through the Scotland Act to implement its reforms. We set up the Silk Commission in Wales that led to a refreshed Wales Act.

“That work to ensure strong devolution within the United Kingdom continues to deliver. It requires a commitment to see powers sit at the level that best delivers for our constituents.

“That doesn’t just mean seeing things through the lens of central and devolved government.

“It means making sure the right powers are closer to communities. So we are committed to devolution for the long run.”

He will argue that while SNP ministers in Edinburgh have “a long-standing aspiration to replace that system of strong devolved government within a United Kingdom” the UK Government “will champion devolution as the best way to deliver for citizens”.

He will also use his speech to insist it is “simply not the reality” to say that relationships between the two administrations are “at their ‘lowest ebb’, stalled, or broken down”.

While there are “very clear differences” between the governments in Edinburgh and London “on matters of substance and great importance”, Mr Lidington will say that these “divergent views – however strongly felt – have not prevented us from working together”.

He will add: “Intergovernmental relations are not defined by fixed moments, or set-piece events. Good relationships don’t begin and end with a meeting in Bute House or Downing Street.

“It is a culture of joint working and constant dialogue embedded between the governments that continues in the background away from the headlines.”

But SNP MSP George Adam complained of a “complete lack of respect” from Westminster towards Holyrood.

Mr Adam stated: “The Tories are using Brexit to ride roughshod over devolution – first with a power grab of devolved issues, and now with threats to bypass our democratically elected Parliament on public spending.

“This is symptomatic of a complete lack of respect – despite three years of discussion, the UK government has not adopted a single Brexit proposal from the Scottish or Welsh Governments.

“No wonder the latest polling shows people are increasingly looking at independence as the only way to protect Scotland’s interests.”