During the 21st century, London may have been the home of a professional baseball team, the London Kings, who were established in TNG: "The Big Goodbye" and DS9: "If Wishes Were Horses". However, since the team was a member of Major League Baseball (they played in the World Series, which is an MLB trademark), whose teams have traditionally been based in North America, it is equally likely the team could have been based out of London, Ontario, Canada. The current home baseball team of London UK is known as the London Warriors.
The pages seen in the "The Big Goodbye" were from the detective novel, The Listening Man, by author John A. Moroso. This novel was published in 1924. Information on London was from page 138.