After the birth of her fourth daughter, she said she wanted to do something completely different.
"My aunty used to be the head trainer for Harcourts, and she told me to go Harcourts because their training was so good."
Mrs Slater said she did not think she had a chance of winning, after only selling for seven months.
"I won the Harcourts regional rising star, then we had the nationals against each of the regions."
She thought that was it after winning that. "Then I got an email from head office. Little me in Greytown, against every agency in the whole of New Zealand.
"And then I won. It was a shock - I was gobsmacked."
Asked what her secret was, Mrs Slater said she and her husband had bought and sold many properties in the past.
"I wanted to be everything different to people who had irritated me in the past.
"Being a woman of my word makes a huge difference.
"I'm not a suity person, I'm very real. I'm just me."
Her award was one of 27 categories, among a potential pool of 12,000 agents in New Zealand.