The problem with classifying block planes is that there is so much variation in features, it’s sometimes hard to pinpoint a particular date. Consider the picture of the Stanley No.18 block plane below, from a 1898 Stanley catalog. The plane has the “handy” finger hold (1897), the lateral adjustment lever (1895), and the early clamping lever (1886). It’s difficult to see, but the lever cap looks as though it has the Stanley patent information on it.
So this looks similar to one of the Stanley No.18’s I described in a previous post (shown below). The only difference on that No.18 is the older style clamping lever (with no patent information inscribed), and interestingly the eccentric lever (patented 1894). So this may actually be a realistic interpretation of a Stanley No.18 of the period (before I blindly swapped the lever caps to fix the disposition of the other mixed up No.18!).
Future post: evolution of throat adjustment mechanisms.