"It was really good-quality museum pieces. And there will definitely be a ready market for it.
"They won't get anything like what it's actually worth, but that won't worry them. They'll just be after some cash so they can buy their P, and they won't have much trouble finding a buyer."
Kauri gum was now "worth its weight in gold", he said. Once weighed in kilos, it was now valued in grams, depending upon its quality.
"And it was so brazen," Mr Johnson added.
"They probably knew someone was living on the premises, but that didn't seem to bother them."
They had also used the crowbar to break into a vehicle parked immediately outside the premises.
Mr Johnson said things were a bit quiet at this time of year but he had had a good season, and the park was open for business as usual yesterday.