A simple calculation, based off of Britannica's definition of stone, results in 9 stone being equal to 126 pounds. One st. is equal to 14 lbs.
The stone (st.) is a British unit of measurement used primarily as a method of measuring the body weight of humans and animals, much in the same way as the lbs. is used in the United States. Originally, once a size was chosen for the st., it was used as a unit in trade. While a st. is standardized as 14 lbs. avoirdupois, or 6.35 kg, historically it has varied anywhere from 4 to 32 lbs. until 1389, when a royal statute created a fixed standard (to be used for wool exportation), due to complications in trade between the British trade market and that of Florence.