The history of Malcolm Turnbull's prime ministership might have been very different were it not for an extraordinary blind spot that he claims prevented him from seeing the threat of Peter Dutton.

Turnbull is, famously, a man of remarkable intelligence. In his autobiography A Bigger Picture, which includes his account of his time, and eventual downfall, as prime minister, he acknowledges an extraordinary failure of judgement around Dutton.

Dutton was the cloddish Queenslander who, during the Coalition's time in government, blundered through the health portfolio and then repeated the underperformance in Immigration/Home Affairs -- the portfolio that has emerged as by far the most incompetent and scandal-prone department in the Commonwealth.