The extent of coverture in medieval England has also been qualified by the existence of "femme sole" customs that existed in some medieval English towns. This granted them independent commercial and legal rights as if they were single. This practice is outlined in the custumal of Henry Darcy, Lord Mayor of London in the 1330s, allowing married women working independently of their husband to act as a single woman in all matters concerning her craft, such as renting a shop and suing and being sued for debt. The custom is known to have been adopted in a number of other towns, including Bristol, Lincoln, York, Sandwich, Rye, Carlisle, Chester and Exeter. Some North American British colonies also adopted this custom in the eighteenth century. However, it is unclear how many women took up this status, the extent to which it was legally enforced, or whether the legal and commercial independence it offered were advantageous.