Robertson, who had attended the United Women's Convention the previous year, said that she couldn't believe what she was hearing.
She saved more and went to the bank later that year with a 33 percent deposit, only to be just to be told that she could only get a mortgage if a male relative guaranteed the loan.
"My father had been dead for years and my brothers had family of their own," she said.
When Robertson discussed the issue with a younger female colleague who along with her husband had secured a mortgage, the response was: "Oh, but you don't need a house, you are not married."
Robertson also noted that a younger single male teacher she knew qualified for a mortgage with a much lower deposit.
She raised the issue of single women being locked out of finance with local National MP Colleen Dewe and was told she should be happy to have the vote.
Fast forward to the 1980s and the situation hadn't changed significantly. When Auckland writer Kate Williams applied for a mortgage in 1982 she was told her father would need to co-sign.
Williams, then 25, was prompted to buy after seeing a female friend do so. As a child of the 1970s feminist movement it never occurred to her that women would be treated any differently to men by lenders.
Like Robertson, Williams found when she went to the bank a higher deposit was needed.
"The first banker I went to just laughed and said 'no'," she says. "He didn't have to give a reason. In those days you sat in an office with an older grey haired (besuited banker) and you felt like a supplicant."
Williams withdrew her money from the bank and invested it with Fay, Richwhite & Company, a non-bank lender. Fay Richwhite agreed to lend Williams a mortgage but only with her father co-signing.
Being Māori could also be an impediment to getting a mortgage in the days when bank managers made value judgements.
Even now the more Māori you look the harder it is to get a mortgage, says University of Auckland social psychologist Carla Houkamau.
Houkamau and colleagues' 2015 study examined differences in the rates of home ownership between Māori who looked Māori and those who didn't. The results found that Māori who looked more Māori were stereotyped and had more difficulty accessing finance.
Robertson says buying first homes wasn't anywhere as easy in the 1970s as first time buyers now perceive. Many of her peers had to get second and third mortgages.
Those that bought new homes got the home only and had to add paths, letterboxes, fences, driveways, and garages later when they could afford to.