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British Museum website: "After the 1607 painting by Jan Brueghel the Elder in the Metropolitan Museum, New York, inv.no.1974.293; a smaller version on copper is in the Alte Pinakothek, Munich, inv.no.1895. The two horsemen in the forest at left are not included in the drawing. A preparatory drawing was sold at auction in Leipzig in 1930."
For the "preparatory drawing" see Winner 1961, fig. 24. I agree that this could have been a design for the general composition, yet the paintings were clearly generated from one another or from some more complete drawing, not from this one -- they repeat the full staffage very exactly from one to the next. What then was the role of a drawing like the Leipzig one?