Holden, meanwhile, chairman of the Republican Movement of New Zealand, Government energy analyst and IBM sales representative, was bemused that a detective from the threat-assessment unit called him to ask what plans he had for Charles' visit.
"He actually confused us with the Republic of New Zealand Party." Holden had repeatedly distanced himself from the former RNZP.
Police did not return messages seeking comment.
Security expert Dr Paul G. Buchanan said it was normal for police to plan ahead and "tell some of the loudmouths to shut up".
"Ninety-nine per cent of the time that dissipates the problem, if there was a threat in the first place."
He said the more serious the perceived threat, the less likely police would contact people of interest directly.
Prince Charles and Camilla, the Duchess of Cornwall, will visit from November 10-16.