A pin cylinder assembly (20) including a housing (22), a cylinder barrel (26), a first set of pin openings (38) and at least a second set of pin openings (40). The housing (22) has an opening (24) therein. The cylinder barrel (26), which has a key slot (28) therein and has a longitudinal axis (x-x), is pivotably mounted in the opening (24). The cylinder barrel (26) includes a set of barrel pin openings (30) therein. The first set of pin openings (38) are in the housing (22). The at least second set of pin opening (40) are also in the housing (22), and are angularly spaced apart around the cylinder barrel axis (x-x) from the first set of pin openings (38). The housing (22) and the cylinder barrel (26) are adapted such that a correctly coded key (58), used for barrel rotation, is removable from the cylinder barrel (26) when the cylinder barrel (26) is in a first position, in which the set of barrel pin openings (30) is aligned with the first set of pin openings (38) in the housing (22), and also in at least a second position, in which the set of barrel pin openings (30) is aligned with the at least second set of pin openings (40) in the housing (22).