She feels at loose ends without her little book, so as soon as coat season arrives, into the pocket it goes.
Sherlock had given her the first book, some years ago, once he noticed how much keeping lists helped her think. Now all the lists are in one place: The shopping, of course. Important phone numbers. Television shows she wants to try. Things the boys might need; they have so much trouble minding themselves. In her pocket, always.
It comforts her to know that, if she should drop dead at Tesco one day, she won't be any trouble for anybody.