General Stud Book
The Jersey Act did not prevent the racing of horses containing the banned bloodlines, as horses with the suspect breeding raced and won in England, but they were considered to be "half-bred". A number of American-bred horses carrying the lines of Lexington had already been imported into England, including Americus, Rhoda B, and Sibola, and because they were grandfathered in, they and their descendants were allowed to be registered in the "General Stud Book". Nor did it prevent the racing of horses that were not registered in the "General Stud Book"; it just prevented registration in the "General Stud Book". American bloodlines, whether registered in the "General Stud Book" or not, dominated English racing in the 1920s and 1930s. Horses that were ineligible for "General Stud Book" registration, but were allowed to race, were identified with a Maltese cross in programs and auction listings.