Is this the best the Conservative and Unionist party can do? Really? The extraordinary thing about Boris Johnson’s campaign to become the country’s next prime minister is that even the people supporting him do not think he’s up to the job of being prime minister. The best that may be said of him is that he may defeat Jeremy Corbyn though, frankly, I wouldn’t want to bet on that.

But, his friends and allies say, you can set aside your concerns about Johnson’s suitability for the highest political office in the land. He will have help, you see. He’ll be surrounded by good people – though this is also something we are asked to take on trust – and they will limit the damage he can reasonably be expected to cause.

Extraordinarily, this really is the argument that is being made. Consider the endorsement of Johnson published by Conservative Home this morning. “Left to himself”, Paul Goodman writes, “he wanders off into scrapes, puns and odium”. Quoting Dominic Lawson, Goodman concedes Johnson is “epically unreliable”. There will be “storms as well as sunshine” but “malice is notably absent from his list of faults”. Well, maybe, though ‘not being a psychopath’ seems a pretty low bar for a would-be prime minister to clear.

Perhaps Tory MPs and Tory members really are the cheapest of cheap dates, however. That is certainly the impression given by Johnson’s supporters who cannot, in all honesty, point to a single notable or qualifying achievement in his political career that indicates he has the chops to make a decent fist of being prime minister. Waving flags at the Olympics does not count.

Hark at Goodman, however, who writes of Johnson that: “Minded and directed, he is more than capable of real achievement”. This is the sort of thing you more usually see on a school report, not in an endorsement of someone aspiring to be prime minister. But it is of a piece with what we hear from plenty of Tory MPs: don’t worry, he might not be as bad as you think because he will be managed by good people.

I do not for a second suggest a Johnsonian ministry would play out in the same way but I cannot help but recall that this was exactly what was said about George W Bush during the 2000 presidential campaign. Sure, he appeared to know very little about the world and was not obviously over-burdened with some of the qualities associated with successful presidents but look at the people around him: Dick Cheney, Donald Rumsfeld, Condi Rice, et al were serious people, well-placed to guide the novice president.

The best indicator of what a prime minister will do in office – and how they will behave in office – is what they have done and how they have behaved before reaching that office. Growth is possible, of course, but transformation of character is highly improbable. They are who they are and it’s not often men in their mid-50s suddenly become new people. At least, not in a good way.

Hitherto Johnson has scarcely deigned to say very much during this campaign. For good reason, since the person most likely to torpedo Boris Johnson is Boris Johnson. But not even Johnson can stay silent forever. He has a column to write for the Daily Telegraph, after all.

Characteristically, his first policy suggestion – raising the higher threshold for income tax in England, Wales, and Northern Ireland, from £50,000 to £80,000 – combines flippancy with cynicism. It is to be “paid for”, in part, by the money put aside to deal with the adverse consequences of a no-deal Brexit that will be avoided by Boris Johnson’s hitherto unseen ability to renegotiate the Brexit agreement reached with the EU. But if that fails, no big deal because no deal is actually a great opportunity for Britain. Whatever else it may be, this is not serious.

Doubtless this giveaway will be jettisoned as soon as its purpose has been served. It’s something to be understood as a campaign promise which is some distance removed from being an actual promise. Never mind the things I said then, prime minister Johnson will say, for those were only aid then and now is not then. A new reality is with us now. You shouldn’t have voted for me if you thought I actually meant any of this and I don’t know why you’re all so determined to take me seriously.

A £3,000 pound giveaway to the wealthiest taxpayers of working age and a £6,000 giveaway to the very wealthiest pensioners is an idea, I suppose, but one that is, intellectually speaking, moribund. The Conservatives’ single greatest weakness is the perception they are the party for the already wealthy. Johnson’s campaign “promise” reinforces that negative perceptive. With bells on.

Never mind that it’s so ill-baked it doesn’t even reach the status of being half-baked. These, I suppose, are only numbers and numbers can be produced anytime, from anywhere, to signify anything.

Even so, it is worth observing that in addition to promising riches to the already rich – and this is so even if you are, reasonably, concerned about fiscal drag – Johnson proposes a measure to cut income tax for the wealthiest in some parts of the United Kingdom that will, in part, be “paid for” by an offsetting increase in national insurance contributions across the whole of the United Kingdom. (Most income tax is devolved in Scotland but NICs are not; I am not surprised Johnson appears unaware of this.)

In any case, Johnson’s promoters claim he’s really a “One Nation” Tory at heart. Maybe so. But his central tax policy, like his central Brexit policy, is not a One Nation policy at all. We are asked to believe in the existence of a Boris Johnson wholly unlike the Boris Johnson we actually see before us.

Well, maybe this other Johnson does exist. But “Trust me, I don’t believe the things I’m saying” is a curious pitch for being prime minister and only a little more alarming than the possibility he does. And when even the people backing him don’t believe he can do the job, why should anyone else?