The Te Tii B3 Trust, which owned the land the Thomsons' house was on, had a no-pets policy and had objected to their plans for a sanctuary.
"Imagine a district in which every household had five cats, with no rules of confinement. The area would be overrun by cats and natural species would have no chance of survival," she said.
"And why would you have 20 cats? You wouldn't need 20 cats to sit on your lap after a hard day's work."
Mr Thomson said there were several cats in Waitangi despite the Te Tii B3 Trust's no-pets policy. Many of them were strays, living "unnatural, miserable lives".
The Thomsons believed they were performing a service by neutering any cats they took in. The problem was caused by irresponsible owners failing to neuter their animals.
"We believe we are part of the solution, not part of the problem," he said.
The Thomsons planned to build a catproof fence around their back garden. They had also sought a legal opinion, which found their property was exempt from the trust's no-pets rule.
The council agreed to allow the Thomsons to keep up to 20 cats subject to a raft of conditions, including a fence to keep the cats confined, annual vet checks, and consent from immediate neighbours.
Cr Ann Court said the issue was not about law but about being good neighbours. The council's conditions set a high threshold which the Thomsons accepted they might not be able to meet.
A separate catfight has raged in Paihia for several years around a volunteer group feeding stray cats on the Village Green. The environmental group Bay Bush Action, which is working to restore wildlife in the nearby Opua Forest, objects to the cat colony. The council's solution is to allow a feeding station on a School Rd verge while it seeks a location for a permanent cat enclosure.