Why does it say Late 19th Century in the movie National Velvet (1944) if it is set in 1920s?

I thought the movie was set in late 19th century when I was watching the movie until the moment I saw the van in later part of the movie.

If it were set in 1920s, why did it say Late 19th century when the movie began?

Why does it say Late 19th Century in the movie National Velvet (1944) if it is set in 1920s?
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