The high-profile 2004 skirmish left him humiliated and out of Parliament. But Mr King appears to be back, embarking on a series of presentations to local Liberal Party branches. The unlikely topic? The threat of a nuclear strike by North Korea.

In a softly lit upstairs room in Paddington's Lord Dudley Hotel on Tuesday night last week, Mr King outlined a doomsday scenario reminiscent of the Soviet nuclear panic during the 1950s, perhaps appropriate given the average age of the 30 or so supporters in the room.

Joining Mr King was lawyer Matthew Bransgrove, co-author of what was being touted as a "civil defence plan".

At the outset, the pair declared the threat of a North Korean nuclear strike so real that it warranted establishment of a 2000-kilometre "submarine exclusion zone" around Australia to guard against attacks.

These included the prospect of North Korean suicide bombers in submarines that, to avoid detection, would be made of fibreglass and could "employ a snorkel and travel at night under diesel power".

"A submarine attacking Sydney, for example, would surface once it had passed the Harbour Bridge and continue up the Parramatta River to the weir at Rydalmere before detonating," Mr King warned.

"Australia is utterly defenceless against such a suicidal submarine attack".

A barrister and member of the naval reserve, Mr King argued that North Korea's intercontinental ballistic missile tests meant its leader Kim Jong-un "will hold the power of life and death over us all very soon".

To prepare for a possible attack, Mr Bransgrove proposed that the federal government assessed "underground car parks, subways and road tunnels" as potential public bomb shelters.

He suggested two compulsory and "unannounced drills" should take place in every Australian city annually, one on a week day and one on a weekend, and there should be a network of early warning sirens established across public buildings.

Notably, Mr King's speech also took aim at the federal government's response to North Korea's threat to target Australia and declared "leadership is required" to implement his plan.

Mr King compared Mr Turnbull's response that Australia had "extensive arrangements with our allies, in particular the United States" with that of former British prime minister Stanley Baldwin who, during the 1930s, "buried his head in the sand as Germany begun its rearmament".

The speech - to members of the Liberal Party Woollahra branch - is the first of several Mr King hopes to deliver. An event is planned for Vaucluse members in a fortnight and another is slated for Bellevue Hill.

It has prompted speculation Mr King may be positioning himself for a return tilt at preselection for Wentworth, possibly if Mr Turnbull quits politics if he loses the leadership or the next election.

Mr King did not respond to a request for comment. For the moment, the focus appeared to be squarely on Kim, his missiles and, as one attendee put it on the night, "scaring the pants off everyone".