This is one of the legendary extinct fighting breeds from Britain, but the true heritage of the Scottish Blue Paul is unclear. One of the theories claims that it was developed from old English mastiffs, European bulldogges and Irish working terriers by the pirate Paul Jones in the 1770's, while others trace its roots to the dogs created by Scottish Gypsies from common pit dogs crossed with blue Greyhounds and Indian Poligar Hounds. It is also possible that some Italian hunting, fighting and guarding dogs brought into the region by traders and pirates have had an influence on the breed as well. A separate strain of smaller red-coated dogs was known as the Scottish Red Smut and was bred away from the Blue Poll Bulldogge in the early 1800's, although both varieties were commonly found in the same litters.
Larger and more vicious than other fighting dogs of its time, the Blue Paul was reportedly impossible to defeat in the pits. With the demise of fighting and baiting sports, the breed is believed to had finally become extinct in its homeland during the last decade of the 19th century, but not before influencing certain bloodlines of Irish game dogs, creating a blue variety within the Irish Staffordshire Bull Terrier. Although a few specimens were reportedly seen in England as late as 1920's, it is unlikely that they were pure examples, as the breed has already disappeared in in its true form in Scotland and Ireland by that point. A small number of Blue Paul Bullterriers was introduced to the United States by Scottish and Irish immigrants, where they became assimilated into the bloodlines of early American fighting dogs. In recent years, some fanciers attempted to trace all blue-coated American Pit Bull Terriers to the legendary Glasgow dogs, but this theory hasn't been proven.
The coat came in a wide range of blue-based colourings, including solid blue, blue with white markings, blue-n-tan, as well as blue brindle, with or without patches of white on the chest and feet. Average height was around 23 inches.