On September 1, two years ago, Nicole was struggling with a buggy and three children in the heat of the day when her phone rang. It was her older sister, Lisa.

'I didn't answer because I was working,' she says. Nicole is a childminder. Her phone rang again. And again. Finally, Nicole called back. 'What do you want?!' she said. 'I'm hot and tired. Why is everyone ringing me?'