Some sign owners were angered by the crackdown, saying it was "madness" and had initially refused.
Now just two sign owners were claiming "existing use rights" and the council was still investigating their claims, said Mr Buchanan.
Cobblestones Museum said consent was given to it in the past for its sign and Mr Buchanan said there was a strong possibility it was.
Resene Paints had also left its sign up.
"He'd [the owner] claimed existing use rights as well."
Under section 10 of the Resource Management Act, signs can remain, breaching the plan, for several reasons, one of which included if the sign was put up before the plan existed.
Different rules apply to signs that don't advertise businesses, such as tourist information signs and traffic signs.
Temporary signage advertising events is permitted 28 days before the events.
When resource consent for a sign is applied for, the council has to consult the New Zealand Transport Agency, as the owner of the highway. The NZTA generally does not like signs on the side of main highways as it was a high-speed zone and could distract drivers.