Originally Posted by Picchio Special

Yes. I can't speak for every era, but 26-inch wheels were the most common size for racing bikes in pre-WWII England. 27-inch wheels began to become available in the immediate post-war as the new "Continental style" took hold, but didn't really become the norm until after about 1950. Classic British Sports upright-bar bikes also use 26-inch wheels, commonly with a bit wider rims than the club and racing models.