Boris Johnson has once again promised to look at ways of reviving a plan for an M4 relief road around Newport - despite the project being decisively rejected by the Welsh Government.
In an interview with ITV Wales, the Prime Minister said "that will certainly be one of the things that we’ll be seeing if we can take forward."
Road building in Wales is the responsibility of ministers in Cardiff who scrapped the plan in 2019 and the First Minister has repeatedly said there would be no u-turn, "Not while I'm First Minister because I've made my decision and it is an entirely devolved decision."
But the Prime Minister has also repeatedly said - including in his Conservative party leadership campaign - that he would try to find a way to revive the project and UK Government officials believe the controversial Internal Market Bill will provide them with the powers to do just that.
In a new interview with ITV Wales, Boris Johnson has said of the bill, "one of the things that it will enable us to do is to strengthen our ability to support people in Wales, for instance in transport spending."
He was asked if that meant ministers in London would try to force it through if local authorities and Welsh Conservative MPs supported it but the Welsh Government continued to oppose it.
He said: "What we’re going to do is look at projects like the relief road, and I must say it was quite extraordinary that the Labour Welsh government managed to spend £144 million on a study … which they then filed vertically.
"So we'll look at the relief road and look at how to relieve congestion in the Brynglas tunnels, that will certainly be one of the things that we’ll be seeing if we can take forward."
You can see the full interview with Boris Johnson in Sharp End at 11.15pm on ITV Cymru Wales.
A Welsh Government spokesperson dismissed the call.
“This is not a matter for the Prime Minister. The decision about whether to build an M4 relief road is entirely a matter for Wales and the decision has been made.”
If a UK Government were to attempt to "take forward" plans for a relief road in such circumstances it would represent one of the biggest challenges to the devolution settlement since the Senedd was established in 1999.
There would be many hurdles, not the least the fact that planning is devolved and the First Minister's veto is, or should be final.
I say 'should be' because there's a feeling amongst Conservative MPs that if the UK Government makes the money available, if all the local authorities affected support it and if a large enough number of Welsh MPs back it too then there might be a case for something which hasn't yet happened over the last two decades. For that final decision to be "called in" by Westminster.
Could that happen? It would be extremely unlikely but a lot of unlikely things have happened in politics in the last few years and the fact that it's even being put as a hypothesis is striking.
What's more, I've heard within the UK Government sentences such as "there is only one sovereign parliament in the UK," another fact but also one that hasn't been asserted over the last two decades where the talk has been of shared sovereignty and respect agendas.
I've written before about this Conservative government's "aggressive unionism" and it's clear that it is determined to test the boundaries. The Internal Market Bill increases its role in previously devolved areas. You can argue whether or not that's a good or a bad thing, but it is a fact.
When the Prime Minister this weekend launched the Hendy Review into transport links between the different countries, he said, "The United Kingdom is the greatest political partnership the world has ever seen and we need transport links between our nations that are as strong as our historic bonds."
The controversial idea of a bridge to Northern Ireland may have grabbed the headlines but it wouldn't be surprising if improving the M4 in Wales cropped up in the review.
That Boris Johnson keeps saying what he says about the M4, that he will look at it, that it's something "we" will try to "take forward" is equally telling.
It's that he's saying it that is the important thing, not the rules and conventions that it would break if it happened. If the last two years have shown us anything, rules and conventions in politics don't mean what they used to.