Where only one shower is provided, this needs to cater for users of both genders.
For a changing facility to count as an additional amenity, it must be capable of being used independently of any showers, otherwise it could not be considered as two facilities.
A shower which is a mixed gender facility must be capable of being used privately. As such, it requires adequate private changing space associated with it.
Amended to provide further clarification and to add the general principle. 10/11/2016