A cylinder lock and key combination, including a cylinder lock, comprising: a housing having a cylindrical bore accommodating a rotatable key plug, - said key plug having a longitudinally extending keyway for receiving a key blade, - a row of tumbler pins (111,..., 116) arranged for elevational and rotational movement in corresponding cylindrical chambers (111a,..., 116a) in said key plug for engagement with coded V-cut bittings (211,..., 216) on an upper edge of an associated key upon insertion thereof into said keyway, and - a longitudinal side bar which is slidingly journalled for transversal movement in said key plug, - said side bar having having an outer, longitudinal ridge portion fitting into an associated groove in said housing, so as to normally prevent rotation of said key plug in said cylindrical bore of the housing, - said side bar also having a row of inner projecting lugs (151,..., 156) each selectively registering with one or more recesses (111h,..., 116h) in said tumbler pins when said key has been inserted into the keyway, - said side bar being movable sideways by turning of a correctly cut key, while said projecting lugs (151,..., 156) enter into the associated tumbler pin recesses (111h,..., 116h) so that said longitudinal ridge portion is released from said groove and the key plug is permitted to rotate relative to said housing, and - a key, comprising said key blade having: - an upper edge provided with said coded V-cut bittings (211,..., 216), wherein: - each of the lugs in said row of inner projecting lugs (151,..., 156) of said side bar is located at a relatively high level, above a rotary axis of the key plug, when being moved sideways with the side bar into the respective tumbler pin recesses (111h,..., 116h), whereas the outer longitudinal ridge portion of the side bar is located at a substantially lower vertical level than the inner projecting lugs (151,..., 156), namely at substantially a same vertical level as the rotary axis of the key plug, seen in a central vertical plane in the keyway, when the outer longitudinal ridge portion engages with the associated groove in the housing, and - said tumbler pins (111,..., 116) are configured so that each of said pin recesses (111h,..., 116h) is located entirely above the rotary axis of the key plug and also entirely above a lowermost end portion of the tumbler pin (111,..., 116) in a cylindrical outer surface of the tumbler pin and is covered by a cylindrical wall part of an associated one of said cylindrical chambers (111a,..., 116a), without communicating downwardly with the keyway, - whereby each pin recess (111h,..., 116h) is concealed and invisible from an inside of said keyway, even when the keyway is empty. a housing having a cylindrical bore accommodating a rotatable key plug, - said key plug having a longitudinally extending keyway for receiving a key blade, - a row of tumbler pins (111,..., 116) arranged for elevational and rotational movement in corresponding cylindrical chambers (111a,..., 116a) in said key plug for engagement with coded V-cut bittings (211,..., 216) on an upper edge of an associated key upon insertion thereof into said keyway, and - a longitudinal side bar which is slidingly journalled for transversal movement in said key plug, - said side bar having having an outer, longitudinal ridge portion fitting into an associated groove in said housing, so as to normally prevent rotation of said key plug in said cylindrical bore of the housing, - said side bar also having a row of inner projecting lugs (151,..., 156) each selectively registering with one or more recesses (111h,..., 116h) in said tumbler pins when said key has been inserted into the keyway, - said side bar being movable sideways by turning of a correctly cut key, while said projecting lugs (151,..., 156) enter into the associated tumbler pin recesses (111h,..., 116h) so that said longitudinal ridge portion is released from said groove and the key plug is permitted to rotate relative to said housing, and - a key, comprising said key blade having: - an upper edge provided with said coded V-cut bittings (211,..., 216), - an upper edge provided with said coded V-cut bittings (211,..., 216), - each of the lugs in said row of inner projecting lugs (151,..., 156) of said side bar is located at a relatively high level, above a rotary axis of the key plug, when being moved sideways with the side bar into the respective tumbler pin recesses (111h,..., 116h), whereas the outer longitudinal ridge portion of the side bar is located at a substantially lower vertical level than the inner projecting lugs (151,..., 156), namely at substantially a same vertical level as the rotary axis of the key plug, seen in a central vertical plane in the keyway, when the outer longitudinal ridge portion engages with the associated groove in the housing, and - said tumbler pins (111,..., 116) are configured so that each of said pin recesses (111h,..., 116h) is located entirely above the rotary axis of the key plug and also entirely above a lowermost end portion of the tumbler pin (111,..., 116) in a cylindrical outer surface of the tumbler pin and is covered by a cylindrical wall part of an associated one of said cylindrical chambers (111a,..., 116a), without communicating downwardly with the keyway, - whereby each pin recess (111h,..., 116h) is concealed and invisible from an inside of said keyway, even when the keyway is empty.