She had quietly set two tests. The first was how the couple handled a serious challenge together - and the hot air balloon tragedy that claimed 11 lives was a bigger tragedy than they could have imagined.
"Dealing with the whole thing, the accident, the victims' families, the community, the whole thing, she felt that that had been a huge test for us."
The second test was whether they could spend a whole day together in the garden and not argue - and they managed that too.
So Tracey bought a gold ring with a greenstone inset and took it to the brunch.
Mark said: "I was wanting to spend the rest of my life with Chris. I knew I'd get to that point, I guess she's just a lot more organised than I am. She beat me to the punch, and I guess a leap year only comes around once every four years so she had to grab that opportunity."
And the big question ... what was his response?
"You'd have to be a lunatic not to say yes - she's a fantastic person."