The mayor of Greater Manchester, Andy Burnham and the First Minister of Scotland Nicola Sturgeon should, on paper at least, be allies.
Both responsible for a population of millions in tackling Covid. Both in pursuit of greater autonomy for the people they represent. Both keen to see the back of the current incumbent of Downing Street.
So why has the First Minister made an enemy of the mayor with a universal declaration that their bailiwicks are currently mutually off-limits?
Manchester and Salford, as well as Blackburn and Bolton are, the Scottish Government has decided, too dangerous for us to have any contact with their population.
But at the time the decision was imposed, and imposed is exactly what it was, it was safer to travel there than to Dundee.
There was no discussion, no consultation, no communication of any kind, not even a phone call to give prior warning.
Mr Burnham is even on the record as having been informed of the regulations via a question from a member of the public while he was live on air.
Perhaps the First Minister has become too used to being able to treat our own local authorities with disdain and did not appreciate that the mayor of Greater Manchester is a role with significant political clout.
He has now written to the First Minister asking if the Scottish Government will compensate individuals who had holidays booked and are unable to get a refund, as well as businesses that lose trade due to the ban.
There is also the question of whether businesses this side of the border will be compensated by the Scottish Government for bookings cancelled as a result of the new regulations.
And what about families who have been starved of contact with relatives from those areas for 18 months, followed the rules, been double jagged and taken tests to check they were safe only for the visit to be cancelled.
Amid all of this, Mr Burnham's angry response has been dismissed by the First Minister as somehow part of a future bid for the Labour leadership.
But imagine her reaction if the Prime Minister, or anyone else, announced a policy change affecting Scotland, our businesses and our public without consultation?
I cannot imagine any circumstances where this, or any other First Minister, would not be incandescent with rage on behalf of the people they serve.
And I would agree with them.
But as one of the people who the current First Minister does serve, I am not convinced she is in the right here, or that the decision is constitutionally legitimate.
We have all readily accepted for more than a year now that we have to keep our personal contacts socially distant, our travel to a minimum and be content with virtual communication with loved ones.
We have become accustomed to reacting to local spikes in infection rates. having our hopes of reunions dashed and our businesses restricted to the point where their survival and our livelihoods are threatened. But even against that background, this decision does not make sense.
The infection rate in Scotland is climbing. Rapidly. We are experiencing what many claim is a spike created by the controversial fan zone in Glasgow for Euro 2020. But no action was taken over that or the thousands travelling to London.
Scotland has worked closely with other parts of the UK to fight this pandemic, and up until this point there has, with a few notable exceptions, been general satisfaction, even credit given to the First Minister for her management of the crisis.
Every step has been taken carefully, there has seldom been a foot put wrong. But this has the potential to be the proverbial size ten planted right in the smelly stuff.
So why the sudden change? And what power does the Scottish Government actually have to restrict what we do outside of Scotland?
Even in the case of those wanting to travel abroad, the UK Government does not say that you cannot go. You can travel if your destination will allow you entry, but you may face restrictions when you return.
But this travel ban is a major expansion of the Scottish Government’s power in attempting to restrict where in England people from Scotland can go.
There are also significant concerns about how it will be enforced, given that the Scottish Government would need to know where in England people are intending to travel or have been.
One is tempted to wonder whether the Scottish Government took Newton’s law into account? And if they did, what was it that they thought would be the equal and opposite reaction to their action?
Perhaps the analysis was that Scots would feel protected and that it would distract us from that spiking infection rate.
Or maybe that the restrictions would assuage that section of nationalist supporters who tried to impose their own border closure earlier in the pandemic.
It might even have been the ban would anger the English so much that they would decide time had come to be shot of us and pressurise Boris to concede independence.
Whether it was one of those or something else completely, I doubt if those advising the First Minister will be happy with the suspicion that it had little to do with infection rates.
Andy Burnham is currently characterised as the ‘King of the North’ for successfully standing up to Boris over support for the North West earlier in the pandemic.
His administration, and others, are being held up as a future template for devolution in England, by Gordon Brown and others developing proposals for a federation to replace the current UK constitution. A positive alternative to independence.
Surely the First Minister was not playing politics?
Christine Jardine is Liberal Democrat MP for Edinburgh West