It started as a lucky number joke, but like all jokes there is often a meaning beneath, which I think is this. I grew up in a family of seven; mum, dad, four brothers and one sister. Of course, no family begins with seven. By the time we'd reached six it was four brothers. My mum and especially my dad desperately wanted a daughter. When the fifth child arrived, my sister, there was a real sense that our family was now complete.

As the middle child, I guess you could say I've been surrounded by the number seven all my life. For the time being, I'm satisfied that my lists are complete when they get to number seven, so I expect I'll be sticking with it for some time to come.