Ive read a book by him about walking the streets of Victorian London and its very interesting
(Edited 7 seconds later.)

Well, you know, times have changed. Words can change, sometimes in very unfortunate ways.
For example, Dave, look at this comic panel. In American slang at the time, a "boner" just meant a mistake, and the meaning here was that The Joker was going to commit crimes themed around making mistakes. But nowadays, this panel reads horribly wrongly.