According to the Te Papa website, British coinage was made legal tender in 1858, though New Zealand's Colonial Government did not have the authority to strike its own coins. Lower denomination currency used in day-to-day trading was in short supply, and so an alternative was needed.
"Some business owners kept accounts for their customers and tried to get around the shortage of loose change by offering credit, while others gave change in the form of postage stamps and matches," Edwards said.
"Other entrepreneurs, like Mr Hague Smith for example, developed their own 'currency,' tokens usually valued in penny or half-penny denominations that could be redeemed at their outlets."
The tokens encouraged people to return to the store, but customers were frustrated by the fact that they could not be used elsewhere. And if the business failed, the tokens became worthless.
"Although tokens were never legal tender, they were an important part of the economy," Edwards added.
"According to Te Papa, which has a number of these tokens in its collections from all over the country, it was estimated that in 1874 half of the copper coins circulating in New Zealand were tradesmen's tokens."
Almost 60 traders in New Zealand are understood to have issued their own tokens between 1857 and 1881, however their use declined after 1876, when a large supply of imperial coinage became available. They were eventually phased out in the 1880s.
The Whangaruru coin was a chance find, literally lying on the sand waiting for someone to pick it up.
"We didn't dig for it, which is important to note, as under the Heritage New Zealand Pouhere Taonga Act it is illegal to undertake earthworks that could destroy an archaeological site without an archaeological authority," he said.
"As an archaeologist, I know the importance of context when an artefact is found – understanding how it sits within an archaeological site can provide us with all sorts of information, which the archaeological authority process enables us to capture. The coin was a one-off find, however, with no archaeological context at all, so in this case it was fine for us to pick it up."
Anyone who found taonga tuturu (Māori cultural objects), on private or public land, were advised to take them to their local museum, which would notify the Ministry for Culture and Heritage. (Go to https://mch.govt.nz/nz-identity-heritage/protected-objects/taongatuturu) for more information.
Given the local connection, he had been happy to offer this find to the Russell Museum for its collection.