Not long ago I was having a conversation with a friend of mine and we were discussing what seems to be an out of place object in The Canon. It can't be an anachronism as it was written into the text during the time it was supposed to be taking place. If it were a newly written case and mentioned an electric refrigerator at 221b, that would be an anachronism. In this case, however, the term "tennis shoes" only seems out of place.
I can recall the first time I came across those words in 'The Adventure of Charles Augustus Milverton' (CHAS), too, and came to a dead stop. "Tennis shoes?" I said. "They had tennis shoes back then?" Well, yes. It's amazing to think that the actual phrase is still in use, unchanged, since that time, but it is. They were usually described with the adjective 'rubber-soled', but not always.
In CHAS Holmes is going over the equipment he has for the break-in at Milverton's and asks to make sure Watson has the correct footwear for such an endeavor.
"This is a first-class, up-to-date burgling kit, with nickel-plated jemmy, diamond-tipped glass cutter, adaptable keys, and every modern improvement which the march of civilization demands. Here, too, is my dark lantern. Everything is in order. Have you a pair of silent shoes?"
"I have rubber-soled tennis shoes."
Rubber-soled shoes have been around since the 1830's. At the time they were called 'sand shoes' but later had the nickname 'plimsoll shoes'. The term plimsoll, which came into use in the 1870's to describe footwear, was used because the shoe had a horizontal seam or line that ran around the outside. It was said to resemble the plimsoll line on a ship. That's the line that the vessel settles at in the water. Above it, it's dry. Below it, it's wet. Same kind of thinking applied when the nickname was given. In time it was discovered that the shoes were good for other activities, and someone eventually caught on to the fact that they would be good for physical education in school. About the same time people started wearing them for lawn games like tennis and croquet. Once patterns were put on the bottom and the grip began to improve, then British Army became interested and started putting in orders. Years later it seems that Watson still had his pair and used them for late-night chicanery in CHAS. If you look at Sidney Paget's illustration you'll see that what he's wearing resembles the above vintage plimsolls.
Women's shoes at the time of Holmes were not quite as comfortable. Ladies were still expected to look and dress a certain way. Even while playing sports of any kind they had to retain the dresses, head wear, and boots of a dignified person. (The men were certainly luckier in the shoe department.) This illustration from 1870 shows people playing croquet. You can just see the woman's boot sticking out. At this time rubber hadn't been added to most of them and this had to be uncomfortable to recreate in. Sadly, it would be about another twenty years before a "rubber-soled tennis shoe" was introduced for ladies.
This piece from Punch in August of 1878 shows basically the same scene. Again you can see the woman's boot, and here she's complaining about it. This type of grumbling was likely very common (and definitely understandable) as outside activities were becoming more popular among the ladies. By the 1900's women were playing more lawn-type games. Someone finally decided it would be a good idea to produce a shoe for them that was similar to the men's.
The ultimate point of my work here at Historical Sherlock is to find ways to help date the stories. I am always looking for things that help confirm that The Game is not in vain, and that it is possible that The Dynamic Duo actually walked this earth. Unfortunately, the only conclusion we can draw here is that Watson wasn't out of place and time when he mentioned "rubber-soled tennis shoes" and that once again The Canon is correct about something. It can't help in our dating of CHAS or any other case, but at least now we know we can eliminate this from the list of those things.