THERESA May’s legacy as Prime Minister will be the end of the Union, Nicola Sturgeon has claimed.

Speaking as the Tory leader heads north for what will likely be her last official trip before leaving Downing Street, the First Minister said May had destroyed the claim that the UK was a partnership of equals.

The outgoing Prime Minister is due to use her visit here to launch a probe into the relationship between Whitehall and the devolved administrations.

The review, which will be led by Tory peer and former Scotland Office minister, Andrew Dunlop, will “consider whether the UK Government structures are configured in such a way as to strengthen the workings of the Union, and to recommend changes where appropriate".

READ MORE: Who is Lord Dunlop, the shadowy Union figure behind May’s devolution review?

There is a long-held belief among some Scottish Tory MPs that the UK Government doesn’t push hard enough to get credit for its spending.

Those frustrations were echoed over the weekend by Boris Johnson who told a hustings in Carlisle: “It’s ridiculous there are so many things, investments that takes place in Scotland indeed other nations of this country, where it is the devolved authority, be it the Scottish Government or another, that always claims credit for what was really a scheme or investment from the UK."

It’s understood that Johnson and Hunt, who will take part in a hustings in Perth tomorrow, have signed up to the review, though neither will be bound by it.

In her speech, the Prime Minister is expected to say: “I am confident that whoever succeeds me in 10 Downing Street will make the Union their priority.

“He will be building on work done over the last three years, during which time strengthening the union has become an explicit priority of government.

“The job of prime minister of the United Kingdom of Great Britain and Northern Ireland brings with it privileges and responsibilities which you only really feel once the black door closes behind you.

“One of the first and greatest is the duty you owe to strengthen the Union.

“To govern on behalf of the whole United Kingdom, to respect the identities of every citizen of the UK – English and Scottish, Welsh and Northern Irish.

“And to ensure that we can go on facing the future together, overcoming obstacles together, and achieving more together than we ever could apart – a union of nations and people.”

The National: Boris Johnson is the clear favourite to succeed May as Tory Prime MinisterBoris Johnson is the clear favourite to succeed May as Tory Prime Minister

Responding, Sturgeon said it was too little too late: “Scotland is heading inexorably towards independence – that will be Theresa May’s legacy.

“The Tories’ behaviour towards Scotland in the three years since the Brexit vote has been high-handed, arrogant and dismissive.

“They have demolished any notion of a respect agenda and have destroyed their own claims that the Union is in any meaningful way a partnership of equals.

“People across Scotland can now see that more plainly than ever. The Tories are clearly running scared of the rising tide of support for independence – and of support for holding an independence referendum, which is now the majority view across Scotland.”

Lesley Riddoch: May's devo review won't stop tide turning towards independence

“Theresa May’s so-called review of devolution is too little, too late – it is reminiscent of John Major’s doomed ‘taking stock’ exercise in the 1990s, which only accelerated the pace towards the devolution referendum and the creation of Holyrood.

“This is Theresa May’s last visit to Scotland as Prime Minster – but there is nothing that her successor, whoever that is, can do to undo the damage to the Unionist cause which has been inflicted during her premiership.”

Recent polls show increased support for independence if Johnson wins.