You’d trust her with your life, is what I mean.

I asked Mrs Wallace what exactly it was about Ruby and Steven’s press conference that prompted her to call Crimestoppers. She put her cup straight down into her saucer and said, ‘It was a no-brainer! The minute I saw the footage of Snow Delaney’s house . . . well, I nearly fell off my chair. I turned to my husband, and I said, “That’s where I took Polly that time!”’

Polly is Mrs Wallace’s foster daughter. She’s been in care since she was born, mainly because she has a range of physical and intellectual disabilities. Polly would be coming up to her 19th birthday now, but her IQ is probably that of an eight-year-old. She has lived with Mrs Wallace and her husband, Brad, since 1994.

‘A lot of foster carers like to say, oh, our foster child came to us sort of by accident! But it wasn’t that way with Polly,’ Mrs Wallace told me. ‘Brad and I, we had three children of our own and once they were up and on their feet and out of home, we decided – or I decided, I suppose you’d say – that I wasn’t ready to have an empty nest.

‘Like most people, I’d heard that there are plenty of children who need good homes, and with our kids gone we had room. So we put our names down to become foster parents. Not that it’s ever as simple as that. There are all these hoops you have to jump through, a mountain of paperwork to fill out, and from memory we were on a waiting list for about a year. Then, on 1 October 1994, and I remember the day exactly, the Catholic Welfare Bureau called to tell us that a little baby had been born, and she was looking for a home.’

The Catholic Welfare Bureau told Mrs Wallace that the newborn’s mother (she can’t be named for legal reasons) was a heroin addict and a prostitute whose last known address was the back room behind the Pink Pussycat in Kings Cross.

‘Staff at the hospital told us upfront that Polly was probably brain-damaged,’ Mrs Wallace said. ‘There’s no use beating about the bush as to why: her mother had tried to abort the pregnancy in the back room of the strip club but she was too far gone. A Maori bouncer had carried her down the street to St Vincent’s emergency and that’s where Polly was born, three months premature.’

‘The staff did their best to try to keep her mum in so she could bond with her baby and maybe even breastfeed, but she wanted nothing to do with Polly,’ Mrs Wallace said. ‘She wanted to get back on the streets and back on drugs, so the Department had to step in and make Polly a ward of the state.

‘That’s when the Catholic Welfare Bureau called us, saying, “This little girl needs a home but she’s going to have significant problems.”’