David Davies - the MP for Monmouth, not the Brexit secretary - has accused Welsh First Minister Carwyn Jones, and Scotland’s Nicola Sturgeon of “wilful sabotage”.

The Conservative backbencher said that by “cosying up to” the EU’s Brexit negotiator Michel Bernier in Brussels, the two leaders were undermining the UK’s negotiating stance.

The trite response to this is “what negotiating stance?” But cynicism aside, the truth is there is not and cannot be any single position. The UK Government has a plan for negotiations, but other interests take different views on the shape our eventual EU departure will take, not least the devolved governments of Scotland and Wales. Mr Jones and Ms Sturgeon have every right to voice those views, and Mr Bernier is fully entitled to explore and even seek advantage from the domestic opposition Theresa May faces.

Ms Sturgeon has insisted she is not trying to open separate negotiations with the EU. But both the Scottish and Welsh Governments have legitimate concerns about how the Brexit process will affect their own powers and by extension Scotland and Wales themselves.

The publication of the Brexit withdrawal bill yesterday is a case in point. It will ensure ensuring EU rules continue after withdrawal from the union, until they can be reviewed by domestic governments.

Mr Jones and Ms Sturgeon declared their dislike of its measures in a joint statement. The bill is a “naked power grab”, they argue and the Conservative government has “failed utterly” to show that it is serious about a constructive collaborative approach with Scotland and Wales.

Scottish Secretary David Mundell rejects claims of a power grab and says that while some areas of policy may benefit from a unified strategy or common standards, both Scotland and Wales cam expect to get a “bonanza” of powers.

But he was woefully vague in saying which powers might return north of the border. Hill-farming was mentioned, environmental and energy issues were hinted at. But fishing rights and other more substantial issues? Conspicuously Mr Mundell said nothing about them.

The restriction which has so offended the Scottish and Welsh Governments is contained in clauses which effectively ban the devolved nations from amending laws relating to powers repatriated from Brussels. Suggestions such powers will return to Holyrood and Cardiff gradually have failed to convince.

There is talk now of a Welsh continuity bill, putting the Assembly on a collision course with Westminster. Nicola Sturgeon says the Scottish Government could not support the bill as it stands.

Through failing to meaningfully involve the devolved nations in the Brexit process, Theresa May and her administration increasingly appear to be fighting on all fronts.

In this, at least, they are undermining their own position.