One aspect of hire purchase about which little has hitherto been known is the length of time that contracts are outstanding. The maximum length of contract has in post-war years nearly always been limited by official controls. Agreements can, however, be taken out for shorter periods; and whatever their intended length, they may be completed before the due date (as may happen, for instance, when a purchaser of a car decides to trade it in for another) or even after it. The completion of a hire purchase contract releases part of a consumer's resources for other purposes, which may include taking out a new contract. So the timing of completions may have an appreciable effect on further purchases of cars and other consumer durable goods.