My day started badly when my little sister was too sick to get out of bed. My mother carted her off to the doctors and they came back with a diagnosis of measles. I'd already had them so it didn't worry me. I sympathized with Marie, made the traditional offer of 'anything I can do to help' and started to head off when she stopped me.

"Yes, there is something you can do," she said, smiling gamely.

"Not a problem," I said, already preparing to run off and bring her back a drink.

"You can babysit the Ferguson's tonight," she said. "They're my best customer and they pay a bomb....