fig1 ( a ) shows an automatic transmission 110 according to an embodiment of the present invention . the transmission has a selector lever 120 operable to rotate a transmission mode selector shaft 122 . the selector shaft 122 is operable in use to select a required mode of operation of the transmission responsive to a rotational position of the shaft 122 . an actuator ( not shown ) is employed to rotate the selector shaft 122 in normal use . in some embodiments the actuator may be an electrical actuator . as shown in fig1 ( b ) the selector lever 120 is bent at a free end thereof to form a c - shaped portion 120 c . a pair of aligned service pin apertures 125 are formed through the c - shaped portion in upper and lower portions thereof ( with respect to the orientation shown in fig1 where the c - shape is substantially upright ). the service pin apertures 125 are positioned such that a service pin 130 may be inserted through the apertures 125 . it is to be understood that the presence of two spaced apart apertures 125 enable a service pin 130 to be held in a substantially fixed orientation with respect to the lever 120 . the selector lever 120 may be rotated manually by an operative from a park position p 1 to a park - released position p 2 . a spring bias arrangement of the transmission 110 urges the lever 120 to return to the park position p 1 when it is displaced therefrom . when in the park - released position p 2 the selector lever aperture 125 aligns with a blind pin - receiver aperture 115 provided in a housing or casing 110 h of the transmission 110 . in use , with the selector lever 120 in park - released position p 2 a service pin 130 may be inserted through the apertures 125 in the selector lever 120 and the pin - receiver aperture 115 in the housing 110 h as shown in fig1 ( c ). the selector lever 120 seeks to return to position p 1 under the bias of the spring arrangement noted above and urges the service pin 130 against a sidewall of the pin - receiver aperture 115 . the selector lever 120 may therefore be held in the park - released position p 2 . the feature that the lever 120 is bent into a substantially c - shaped formation has the advantage that a risk that the service pin 130 becomes dislodged from the pin - receiver aperture 115 is reduced . it is to be understood that if the pin receiver aperture is made sufficiently deep a requirement to provide two service pin apertures in the lever 120 in order to hold the service pin 130 in a substantially fixed orientation may be eliminated . the selector lever 120 may be returned to the park position p 1 by removing the service pin 130 . in the embodiment of fig1 and in some other embodiments the selector lever 120 has a substantially flat surface to which finger pressure may be applied by a user when moving the lever . the presence of a substantially flat surface improves a user experience when turning the lever , reducing a risk of damage to a user &# 39 ; s finger . fig2 shows a selector lever arrangement according to an alternative embodiment of the invention . like features of the embodiment of fig2 to those of the embodiment of fig1 are shown with like reference signs prefixed numeral 2 instead of numeral 1 . in the arrangement shown a transmission mode selector lever 220 is provided having a single bend at the free end thereof , forming an l - shaped arrangement , rather than a c - shaped arrangement . a single service pin aperture 225 is provided through the lever 220 . a corresponding service pin receiver aperture 215 is provided in the transmission housing 210 h . in the embodiment of fig2 the pin receiver aperture 215 is deeper than that of the embodiment of fig1 , being sufficiently deep to allow the service pin 230 to be retained therein without requiring more than one aperture to be formed in the selector lever 220 . it is to be understood that not all transmission housings 210 h may allow a sufficiently deep pin receiver aperture 215 to be formed therein and therefore the arrangement of fig1 may be preferable in some embodiments . it is to be understood that the pin receiver aperture 215 is sufficiently deep to allow a service pin 230 to be retained therein by a pinching action of the lever 220 on the pin 230 . the pinching action is imposed under the restoring force imposed by a spring bias arrangement of the transmission which urges the lever 230 to return to a park position p 1 when it is displaced therefrom as discussed above with respect to the embodiment of fig1 . in some embodiments the service pin 130 , 230 may be operable to become locked in the pin receiver aperture 115 , 215 so as to prevent accidental release of the pin 130 , 230 from the aperture 115 , 215 . in some embodiments the service pin 130 , 230 is shaped so as to enable retention within the aperture . for example in some embodiments the service pin 130 , 230 has a substantially t - shaped free end portion . the service pin 130 , 230 is arranged to be inserted into the pin receiver aperture 115 , 215 and to be rotated once inserted whereupon a crossbar of the t - shaped portion prevents withdrawal of the service pin 130 , 230 by interference with a portion of the transmission housing 110 h , 210 h defining the aperture 115 , 215 . in some embodiments the service pin 130 , 230 is operable to engage the cross - bar with a recess formed within the transmission housing 110 h , 210 h . other means for retaining the service pin 130 , 230 within the pin receiver aperture 115 , 215 are also useful . fig3 shows a selector lever arrangement according to a further embodiment of the invention not requiring use of a service pin . like features of the embodiment of fig3 ( b ) to those of the embodiment of fig1 are shown with like reference signs prefixed numeral 3 instead of numeral 1 . fig3 shows an automatic transmission housing 310 h having a recess 315 formed therein . a selector lever 320 is coupled to a transmission selector shaft 322 and is operable to rotate the shaft 322 when the shaft is in a park position to release the transmission from a park mode . the selector lever 320 has a hooked end , at which a portion of the lever 320 is bent towards the transmission housing 310 h forming a hooked tip portion 320 t . the selector lever 320 is of a bi - stable construction and is operable to assume one of two configurations . in a first configuration c 1 a longitudinal axis a of the lever 320 is substantially straight from the selector shaft 322 to the hooked tip portion 320 t . in a second configuration c 2 the longitudinal axis a of the selector lever 320 bends along a length of the lever 320 towards the housing 310 h such that the hooked tip portion 320 t may protrude into a recess 315 formed in the housing 310 h . the recess is formed in the housing 310 h at a location corresponding to the park - released position of the lever 320 . thus in use with the selector lever 320 in the first configuration c 1 the lever 320 may be rotated to the park - released position and the lever 320 bent into the second configuration c 2 such that the hooked tip portion 320 t protrudes into the recess 315 . rotation of the lever 320 back to the park position is prevented by abutment of the hooked tip portion 320 t with a sidewall of the recess 315 until the lever 320 is returned to the first configuration c 1 . in some embodiments the selector lever 320 is formed from a bi - stable metallic strip arrangement . fig4 shows a selector lever arrangement according to an alternative embodiment of the invention . like features of the embodiment of fig4 to those of the embodiment of fig1 are shown with like reference signs prefixed numeral 4 instead of numeral 1 . in the embodiment of fig4 a transmission selector shaft 422 of an automatic transmission 410 is rotatable from a park position to a park - released position by rotation of a selector lever 420 from a park position p 1 to a park - released position p 2 in a similar manner to the embodiments described above . the selector lever 420 is coupled to an inner cable 441 of a bowden cable 440 . an opposite end of the inner cable 441 is connected to a ring - pull member 454 of a ring - pull actuator arrangement 450 . the ring - pull member 454 is slidable in a barrel member 452 of the actuator arrangement 450 . the barrel member 452 is coupled to an outer sheath 442 of the bowden cable 440 . the bowden cable 440 is arranged wherein the transmission selector lever 420 may be rotated from the park position p 1 to the park - released position p 2 by pulling the ring - pull member 454 away from the barrel member 452 . once the selector lever 420 has assumed the park - released position p 2 a service pin 430 is inserted through an aperture in a stem 454 s of the ring - pull member 454 to prevent the ring - pull member 454 from moving back towards the barrel member 452 . it is to be understood that a spring bias arrangement of the automatic transmission 410 biases the selector lever 420 to the park position p 1 such that if the service pin 430 is removed the selector lever 420 rotates to the park position p 1 drawing the stem 454 s of the ring - pull member 454 back into the barrel member 452 . in some embodiments further biasing means is provided to urge the selector lever 420 to the park position p 1 in order to compensate for any frictional forces imposed by the bowden cable 440 on movement of the lever 420 . it is to be understood that the ring - pull actuator arrangement 450 may be mounted in any suitable location allowing ready access by an operative . for example the ring - pull actuator arrangement 450 may be mounted in a cabin of a vehicle . alternatively the ring - pull actuator arrangement 450 may be mounted in an engine bay or any other suitable location . it is to be understood that the embodiment of fig4 may be particularly useful in vehicles where access to a selector lever 420 mounted on the selector shaft 422 is difficult . this may be the case in particular with longitudinally mounted (‘ north - south ’ orientated ) engine and transmission assemblies . in some embodiments , the ring - pull member 454 may be locked in a position in which the selector lever 420 has assumed the park - released position p 2 by rotation of the ring - pull member 454 . rotation to lock the ring - pull member 454 may for example be rotation about an axis of the ring - pull member 454 along which the ring - pull member 454 is pulled in order to rotate the selector lever 420 . other arrangements are also useful . fig5 shows an automatic transmission 510 according to a further embodiment of the invention . like features of the embodiment of fig5 to the embodiment of fig1 are provided with like reference signs prefixed numeral 5 instead of numeral 1 . a park release lever 520 of the transmission 510 is operable between a park position p 1 in which the transmission assumes a park mode and a park - release position p 2 in which the transmission is released from the park mode in a similar manner to the transmission 110 of the embodiment of fig1 . a hook member 560 is shown coupled to the release lever 520 . in the embodiment shown the hook member 560 is permanently coupled to the release lever 520 although in some embodiments the hook member 560 may be coupled to the lever 520 only when it is required to lock the release lever 520 in the park - release position p 2 . in order to lock the release lever 520 in the park - release position , the lever is swung from the park position p 1 to the park - release position p 2 and the hook member 560 is hooked around a pin element 530 protruding from a housing 510 h of the transmission 510 . the hook member 560 thereby maintains the release lever 520 in the park - release position p 2 . in some embodiments the pin element 530 is permanently attached to the transmission housing 510 h whilst in some alternative embodiments the pin element 530 is fixedly attached thereto . in some embodiments the pin element 530 is releasably attachable to the housing 510 h when required . when it is required to release the transmission from the park - release position p 2 the hook member 560 is unhooked from the pin element 530 and allowed to return to the park position p 1 under the bias of a spring bias arrangement of the transmission 510 . the hook member 560 may be arranged to be held clear of a normal range of movement of the lever 520 when the hook member 560 is not in use . in some embodiments the hook member 560 is arranged to be coupled to the release lever 520 and the transmission housing 510 h only when it is required to hold the release lever 520 in the park release position p 2 . thus the hook member 560 may be provided in the form of an accessory separate from the transmission 510 . in some embodiments the hook member 560 is permanently coupled to the transmission housing 510 h and is hooked to the release lever 520 when required . embodiments of the invention have the advantage that a park mode of a transmission may be released by means of a park release lever in a relatively straightforward manner and locked in the release position . if the vehicle begins to move unexpectedly once the park mode is released the park mode may be resumed by releasing the park release lever before it is locked in the release position . because one or more members must be moved in different respective directions in order to rotate the selector shaft and lock the selector shaft in the brake release position , a risk that an operative rotates the selector shaft and locks the selector shaft in a single action is reduced . whilst embodiments of the invention have been described with respect to a park release function of an automatic transmission it is to be understood that embodiments of the invention may be employed in other transmissions having brake means functionality as well as electrically - actuated park brake ( epb ) systems in which actuation of a parking brake is controlled by means of an electrical actuator . throughout the description and claims of this specification , the words “ comprise ” and “ contain ” and variations of the words , for example “ comprising ” and “ comprises ”, means “ including but not limited to ”, and is not intended to ( and does not ) exclude other moieties , additives , components , integers or steps . throughout the description and claims of this specification , the singular encompasses the plural unless the context otherwise requires . in particular , where the indefinite article is used , the specification is to be understood as contemplating plurality as well as singularity , unless the context requires otherwise . features , integers , characteristics , compounds , chemical moieties or groups described in conjunction with a particular aspect , embodiment or example of the invention are to be understood to be applicable to any other aspect , embodiment or example described herein unless incompatible therewith .