Mr Walters: "For police, it was important that their resources were not tied up in dealing with that. So we contracted in this company to document everything, photograph it, label it, and take it to a secure site and manage its return to each owner.
"We wanted to make sure there was [a] professional, clear approach and proof of ownership process. It was really all about respecting the rights of these [protesters]. There was absolutely no covert surveillance."
Thompson & Clark did not return calls yesterday. Its website says it is a security, corporate intelligence and protection agency helping clients with "the protection of interests, operations and personnel through unique and highly specialised skills and resources".
In 2007, investigative journalist Nicky Hager found that the Auckland company had paid a student to infiltrate environmental group Save Happy Valley for state-owned enterprise Solid Energy. Last year it was caught out attaching a tracking device to an animal rights campaigner's car.