Bull and Terrier
Most terriers, of the past and present, carried or carry a quarter to 1/8th Old English Bulldog blood in them in order, allegedly, to give courage to bear the bites of the prey they are meant to attack. Terriers who were not developed from crosses between the Old English Bulldog and earth-working dogs were of inferior quality and were valued far less.
Not only is the Fox Terrier the progeny of the Bull and Terrier, but so is the Airedale Terrier, rat-working terriers, working black and tan terriers, and most all other vermin-hunting terriers.
James Rodwell described in his book titled 'The rat: its history and destructive nature', that the great object, among the various breeders of Bull and Terrier dogs for hunting vermin and rats, was to have them as nearly thorough-bred bull as possible, but at the same time preserving all the outward appearances of the terrier as to size, shape, and color.
The Old English Bulldog was bred for bull-baiting. Its life depended on "Go Low, Pin and Hold". Such a breed was unsuitable for dog fighting in the pit. Once an Old English Bulldog got a good grip, there would be little left for the spectators to see, except for two dogs gripping each other, closing their jaws tighter and tighter.
Required were quick attacks, new grips, and tricks, which made up the drama of a dog fight that appealed to spectators, gamblers, and dog owners. The introduction of English Terrier blood provided longer legs, fiery temperament, and speed, which provided entertaining fights.
The crossing of bulldog and terrier produced a dog that no longer belonged to either foundation breed. The new dog breeds was called the Bull and Terrier. With attributes such as ferociousness, aggressiveness, and intelligence, there were few fighting tasks it could not perform better than other breeds of those times.