Image copyright EPA Image caption Theresa May: "There is no review into devolution."

The prime minister has denied speculation that she will announce a devolution review on her visit to Scotland on Thursday.

That has been reinforced by a source close to the process who repeated to me, almost verbatim, the words she used to MPs at Prime Minister's Questions earlier: "There is no review into devolution."

Sources tell me she is likely to announce a review of the way the Union of the United Kingdom works. Especially the way Whitehall departments relate to the devolved nations over the issues the UK government is responsible for.

The Secretary of State for Wales, Alun Cairns, has long argued (behind the scenes) that the UK government should cultivate direct relationships with stakeholders around Wales in addition to the Welsh Government - local authorities, business groups, farming unions and so on.

It looks as if his arguments may be bearing fruit.

Sources tell me "it's about recognising that Wales has two governments" and that, for example, when the UK government makes a decision about the economy or business they should ask for the views of business groups in Wales as well as those of the Welsh Government".

Is this a power grab?

Sources insist it's not.

They say it's not about impinging on matters the Welsh Government is responsible for, but about consulting more widely on non-devolved matters that impact on Wales.

But would any of these direct contacts and relationships involve decisions about how to spend public money in Wales?

Image copyright STV/BBC Image caption Ex-Scotland Office minister Lord Dunlop is expected to lead the review

That would "only ever be about additional money" not core Welsh Government funding, I'm told.

Still, it's very hard to imagine the Welsh Government not wanting to be the arbiter of where public money should be spent in Wales.

And given that we won't hear until 2020 how the successor fund to the EU aid money that has given billions of pounds to Wales will work, this review could sound alarm bells in Welsh Government HQ.

Is there a row brewing? We'll find out tomorrow when the details of the review are published.

But Plaid Cymru have already dismissed the review as a "desperate" search for a legacy from a Prime Minister "in the dying days of her forgettable…. premiership".