Ruby’s mobile phone went off once during the interview and she grabbed it, which reminded me how desperate she was to hear something – anything – if not from her mum then from the cops. But it was her husband, Philip, who was upstairs with their kids. He was asking if she was okay, and if he could do anything, and what did she think about him taking their kids over to Luna Park, since they were going stir-crazy in the hotel room?

Ruby said that would be fine, and the kids came down in the lift. I was struck by how much Stella looked like her mum, and how Rocco was a double for his dad.

I stood up when Philip came in – he was very tall. He shook my hand and thanked me for coming, in that formal way British people have. It was warm outside – it was still December – and Philip and the kids were pale and wearing what looked like new, ironed shorts with pleats in the front from somewhere like David Jones.

Philip asked a couple of questions about the best way to get to Luna Park, and I told him that the ferry was enjoyable, and they’d get a good view of the Opera House and the Bridge. I told Rocco that Luna Park had some fun rollercoasters, and he said, ‘I went on a rollercoaster at Alton Towers.’

I told him I was pretty sure the rollercoaster at Alton Towers was better than what they had at Luna Park, but Rocco was mostly looking forward to seeing the Harbour Bridge in any case, which he said had six million rivets holding it together. He was clearly like a sponge when it came to remembering things.

They headed out the glass doors into the hotel foyer. We watched them go, and I couldn’t help thinking that Ruby’s mother had done just that: walked out those doors and got swallowed up into the red mist and never come back again.

This might not be obvious but I was conscious of the fact that I’d need to have a conversation with Ruby at some point about whether her mum had met with foul play. The idea that she was still wandering around in Sydney, lost, might have seemed reasonable in the early days, but not after three months. Something must have happened to her. But, having just seen Mrs Moore’s grandkids skip out the hotel foyer, I suppose I didn’t feel quite ready to raise the subject so I turned back to Ruby and said, ‘You were saying that your mum loved living in Australia when she was a little girl?’ And Ruby, who was doing her best not to get teary again, said, ‘That’s right. Mum’s incredibly proud of having been brought up in Australia. She was only seven when she landed here and she didn’t meet my dad until she was seventeen, so she spent a good decade here, and she’s got wonderful memories of it, such as the time she saw the Queen.’