Is this a trend I'm missing because I keep seeing women on the tube doing what looks rather pointless and impractical - carrying a small paper bag (usually from a designer or cool brand) in addition to their main bag. I don't mean a full sized carrier bag, just a dinky little thing with a rope handle, a small gift bag size really. The woman I saw doing it this morning was carrying a book and her make-up in it (which she was applying en route - another thing I just don't get), but it wasn't really big enough for the book which was sticking out the top.
What is the point?
If there isn't room in your main bag, why not a) get a bigger bag b) take a second proper bag for the overflow. These little bags can hold so little it hardly seems worth the effort, aren't that easy to carry & aren't water-proof. Is it to show-off that you've bought something very small in an expensive shop?