Boo had the run of the land, catching rats and birds and mainly living outdoors.
In 2003 his owner relocated to Rocky Cutting Rd, "out in the wops" between Welcome Bay and Te Puke. But Boo went missing and eventually showed up back at the property in Pyes Pa, where he has stayed.
Ms Clarke and her brother and parents were building houses on the property, and she estimated Boo lived off the land by himself for probably two years.
"Then the kids spotted him again and he came up to the house. We started feeding him but didn't know if he would be tame or what," she said.
"He sort of wandered into the house and then two weeks later was sleeping on my bed every night."
She said he was big and fluffy but had grown quite skinny in his old age.
Boo lived a relaxing elderly lifestyle - eating lunch at her mother's house up the driveway and lying in her garden during the day, and catching the odd rat or mouse when he felt up to it.
"We've only taken him to the vet once last year when he was getting fur balls on his chest.
"Thinking about it, I doubt he's ever been immunised or wormed or deflea-ed."
She said she and her family were stumped at how Boo could have possibly lived for so long.
Tauranga Vets vet nurse Jess Lowe said the oldest cat she had ever treated was 22.
"Twenty-three is a really good age for a cat, definitely getting on."
She said vets were seeing cats getting older and older and with more advanced medicine available many owners were willing to spend the time and money to treat their pets.
"But 23 - that's quite a shock."
She said a lot of people did not realise they could have a cat for that long.
"People get them in their 20s and don't realise they might have the cat into their 40s."
The oldest cat ever is Creme Puff who was born on August 3, 1967 and lived until August 6, 2005 - 38 years and 3 days, according to Guinness World Records.
Indoor cats generally live from 12-18 years of age. Outdoor cats generally live shorter lives due to being more likely to be involved in traumas such as motor vehicle accidents or dog attacks.