Why did Colonel Malcolm mandate that Westies be white after a hunting accident?

To ensure they could be easily distinguished from their quarry, such as foxes.

The standardization of the Westie's pure white color is famously linked to an incident involving Colonel Malcolm of Poltalloch. The narrative suggests that during a hunt, one of his terriers was accidentally mistaken for quarry, leading to a fatal outcome. Following this event, the Colonel implemented a strict rule that all terriers bred on his estates must possess a white coat. This change was purely practical: a white dog would be readily identifiable against the background terrain and wildlife, preventing accidental harm during the intensity of the hunt, thereby solidifying the breed's defining color characteristic.