Given the proximity of the pattern numbers, my guess is that this is a companion piece to Pictorial Review 1435, the Semi-fitted Riding Jacket. It's also clearly related to Butterick 4147, which is calling itself knickers.
Like the Pictorial Review Riding Jacket, the only layout given is for 54" material.
Part of reading clothing is observing it on the body. Here's a wonderful photo from Shorpy of a young Louisita Wood in 1913. Wood's family had money, so I suspect that her riding clothes were custom made for her and that this was considered a good fit.
And here she is seated.
It's not uncommon to find names written on the pattern envelopes. There are several possible explanations for this. One is that patterns sometimes had to be special ordered, and the purchaser's names were written on the envelopes by the store clerk when the patterns arrived from the supplier. Another possibility is that the garment was made up by a dressmaker, and either she or her customer wrote the name on the envelope.
In this case, we have Mrs. Flora Grove, on Winchester Avenue.