I met last night with a senior Conservative MP in a very small gathering (mostly of Tory supporters) under Chatham House rules. It was – even by those standards – a frank and honest discussion. X comes from a Conservative tradition I’ve always had regard for – although it is not my tradition – and I’ve been alarmed to see Tories of that tradition supporting Boris Johnson (“BJ”). In the circumstances I was keen to understand how X had arrived at that destination.

I tweeted a summary of X’s view last night but want to address (1) X’s logic in more detail and (2) some of the responses to my tweet.

The headline was that X believed BJ was the best way to counteract the threat from the Brexit Party. Although X was a Remainer – and believed BJ could pivot to supporting a second referendum – X was also prepared to contemplate what I understood to be a managed No Deal as an alternative to the Corbyn Government that X saw as being the natural consequence of not meeting the Farage threat.

Most of my tribe will likely have our own views about the damage a “managed No Deal” will do. And they are likely to differ sharply from the near equanimity of X. I certainly said so to X. But what I wanted to focus on is what lies on the other side of the balance for X: the fear of a Corbyn government.

X’s concern – and I reiterate that the dinner was unusually frank and honest – was that Corbyn’s would be no ‘normal’ Labour Government. And because of that, keeping Corbyn out had an importance of a greater order.

X elaborated little on why X believed that keeping Corbyn out was so important but I understand, and have some sympathy with, X’s basic point. I worked as a tax advisor to Ed Miliband’s Labour Party and have also advised McDonnell but I have no ambitions to be part of a Labour Government. This means I have no need to be otherwise than frank in giving some colour to what I understand to be X’s concerns. (I should say that what follows is what many of my tribe, including some Labour MPs, say privately about a Jeremy Corbyn Government.)

There is a narrative on some parts of the Left that sees, or finds it useful to portray, a putative Corbyn Government as coming from a moderate European social democratic tradition. But I think, and understood X to think, that narrative is wrong, and sometimes disingenuous.

What is my evidence for saying that? Here are the headlines.

In unguarded moments Labour talks about having the desire to effect an “irreversible” change in the country. That is uncomfortable language to use in a democracy. But more than that: we don’t know what that irreversible change looks like.

Most other countries have proper constitutions but the only higher law to which the UK is presently subject comes from the EU. It offers some constraints on some actions that step outside our collective European norms. Those constraints are limited by the fact that the EU is only able to constrain us where we have permitted it to do so but they do operate with greater intensity in the field of economic policy.

Labour’s leadership is anxious that we should leave the EU. And I find it hard to rationalise this otherwise than by reference to the fact that it wants to jettison the constraints that the EU represents; it wants unlimited power to remake the country. Labour says we need to leave the EU to jettison rules on state aid. But there is nothing in Labour’s 2017 manifesto that EU law would prohibit.

What specific actions does Labour believe EU law would constrain? What more does Labour have planned that it will not come clean about? Before we usher in “irreversible” change, are we not entitled to know what it looks like?

There are, of course, compelling counter-narratives to to the narrative that a Corbyn Government would have unconstrained power to effect irreversible change to unstated ends. Perhaps the most powerful is that he would be limited by the realities of Parliament democracy, a pluralist Labour Party, and the lack of a manifesto mandate. And I suspect X’s analysis, ultimately, understates the limitations imposed by these practical constraints. But I wouldn’t pretend to be completely unsympathetic to it.

More generally X also believed that it was possible to ignore BJ’s work as a paid rhetorician and discover in him the more socially liberal Tory who was London mayor. You’ll have your own view about that but I wonder whether X was really persuaded by the argument.

On the available evidence (purely hypothetically because I will vote for neither) I would choose a Corbyn Government over a Johnson one. But the above is the case, as I understood it, made by X, a senior Tory politician not impossibly far from my own tribe, for the alternative.