Deep down, the majority of Conservative MPs know that the whole enterprise is a warehouse full of snake oil. So there is a twisted logic in giving the sales job to Johnson, their most talented charlatan.
There is only so long that a government can parade a corpse and ask the public to admire it. Tories can dress it up in different costumes, stick a Boris-style wig on it, spray it with perfume, but the idea itself has started to putrefy. Its complexion has turned sallow.