At the beginning of The Magician's Nephew, CS Lewis wrote:
In those days Mr. Sherlock Holmes was still living in Baker Street and the Bastables were looking for treasure in the Lewisham Road. In those days, if you were a boy you had to wear a stiff Eton collar every day, and schools were usually nastier than now.
Considering Mr. Lewis was a very good writer and a language professor, why would he use a comma there and not here? Shouldn't he have used a comma in both sentences, or left it out at all? (I've checked many editions and they all lack the first comma, and have the second.)