Tales of the Folly collects short stories from the Rivers of London series.

I thoroughly enjoyed reading this collection. The stories offer an opportunity to do some extracurricular worldbuilding for aspects of the magic system that don't get mentioned in the main books or aren't enough to build a whole novel on. I thought A Dedicated Follower of Fashion was a particularly fun story and enjoyed getting to spend some time in Abigail's head in Favourite Uncle. Well worth the read!