The Duchess of Cambridge has a bag I like. It's the Aspinal Mayfair Midi bag and it costs £550.
I want something under £100. Small with a shoulder strap, preferably mock croc and in black, navy or dark brown.
Hobbs have a similar-ish leather one in navy (but it looks hard to open with one hand) and Boohoo have a cheapie in black (but I'm assuming it won't last long) .