Boris Johnson has gone on record to say that his bumbling self-deprecatory persona is a “cunning device” he uses to get people to trust him.

Asked in an interview with TV network CNBC whether his “remarkable openness” and “self-depreciation” were typical qualities of a politician, he said: “No I think it’s a very cunning device. Self-depreciation is all about understanding that basically people regard politicians as a bunch of shysters, so you’ve got to be understood.”

He also said he used his sense of humour as a political tool to capture people’s attention. “Most people actually find lots of political stuff incredibly dull,” he said.

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“So if you can make a joke or if you can find some way of illuminating some idea or subject with a metaphor that captures people’s imagination…then you’ve got them for a second.”

Mr Johnson went on to admit, in his trademark self-deprecating manner, that becoming Mayor of London “was a fluke” and later tells a humorous anecdote about when his bodyguard took a photo of his “arse” as he was stuck on London’s zip wire.

The televised interview is the latest in a number the former Tory MP has conducted recently, after his notable grilling by Eddie Mair on The Andrew Marr Show. It is also just three weeks since BBC2 documentary The Irresistible Rise of Boris Johnson went out.

In the interview with CNBC, due to be broadcast tonight, Mr Johnson claims to remember nothing about his “embarrassing time” in Oxford’s Bullingdon Club, saying: “I think the blessed sponge of amnesia has wiped the slate.”

When asked about his future political career, the Mayor of London said he “intended to bash on” but evaded talking about any ambition to become Prime Minister.

“I think most sensible people who know enough about British politics know that I’m jolly lucky to be Mayor, let alone anything else and that’s what I’m going to focus on,” he said.

CNBC Meets Boris Johnson is broadcast tonight at 10pm on Sky(channel 505), Virgin Media (channel 613), FreeSat (channel 210)