‘I took Rocco out to Heathrow, mainly because he had bought one of those silver Welcome Home balloons and he wanted to show it to Mum, and I remember that we were standing waiting in the arrivals hall at Heathrow for so long that the balloon started to slump on its string. At some point, it became obvious that all the passengers were off the flight, and I thought, “Oh no, Mum must have missed the plane!” But that made no sense because she hadn’t sent a message and she definitely would have sent a message.

‘I went over to the British Airways counter, but BA has a policy of not telling you who is supposed to be on which plane – understandable but in those circumstances frustrating – so I looked up the number for the Sir Stanford in Sydney on my iPhone and they said that Mum hadn’t even checked out of the hotel, which was more confusing still.

‘I checked my email on the iPhone – not for the first time, obviously – and there was nothing. Just nothing. And for my mother that was astounding. I called Steven and said, “Have you heard from Mum?” He said he hadn’t and that maybe it had something to do with the time difference, but I knew in my bones that that had nothing to do with it.’

Ruby then called Doug Grenfell, who hasn’t forgotten the conversation.

‘Ruby was very, very concerned,’ he told me when we spoke in his Deer Park office. ‘I told her, you need to call the police immediately.’

Ruby confirmed that account, saying, ‘Doug Grenfell gave me the number for New South Wales police and I called them. I don’t like to complain, but from early on we couldn’t seem to make them understand how worried we were. It was at least three or four days, I think, before they talked to anyone at the Sir Stanford and maybe six days before they spoke to Snow.’

I asked Ruby, ‘And when you came out for the first press conference, what did they tell you? Did they have any ideas, any clues?’

‘They told me they’d tracked Mum’s movements back to the hotel from Snow’s place. She was seen on the CCTV coming from the foyer, and the data from her key card showed that she went back to her room.’

‘And then nothing until she left her hotel room again at 5 a.m. on the day of the dust storm?’ I asked.

‘Not quite nothing: the police told us that Mum made one call from her room on the evening before she disappeared.’

It was the first I’d heard of that, so I probed for more information. Ruby said Agnes made one call from her room the day before she disappeared. It was to 999. That’s the number for police, fire and ambulance in the UK. In Australia, it gets you nothing but a long beep.

Not only that, Agnes had also received one call in her room on the morning before she disappeared. It came from a blocked number, through the hotel switchboard.