[hobolobo]

As Ian Hislop put it:

Boris Johnson, people always ask me the same question, they say, 'Is Boris a very very clever man pretending to be an idiot?' And I always say, 'No.'

[js8]

Boris Johnson is a man of average intelligence pretending that he is an idiot, so in case when something goes wrong and he really looks like an idiot, people wouldn't be able to blame him, since obviously, from the start, he was an idiot!