An electric parking brake actuator mounting assembly comprising an electromechanical actuator that is mounted to a drum brake backplate, - the brake backplate of the drum brake, having a rear surface opposite to a front surface configured to be facing a brake drum when the brake backplate is mounted on a motor vehicle, wherein the rear surface of the brake backplate includes a support base configured to receive a pull spindle of the electromechanical actuator, - a supporting bracket including at least one coupling plate (205, 210), configured to be attached to the rear surface of the brake backplate, and an actuator mounting surface configured to be coupled to and support the electromechanical actuator, wherein the actuator mounting surface includes a spindle seat, configured to receive the pull spindle of the electromechanical actuator, the electric parking brake actuator mounting assembly characterized in that the actuator mounting surface of the supporting bracket further includes a pin lock seat, configured to receive and lock an engagement pin of the electromechanical actuator, the rear surface of the brake backplate is provided with at least one first mechanical member and said at least one coupling plate (205, 210) is provided with respective at least one second mechanical member, wherein said at least one first mechanical member and said respective at least one second mechanical member are configured to engagedly slidably interact with each other, and wherein the spindle seat is configured to be connected to the electromechanical actuator through a bayonet fitting including a release configuration and a lock configuration, and the pin lock seat is configured to lock the engagement pin when the pull spindle is inserted into the spindle seat and the electromechanical actuator is rotated about a longitudinal axis of the pull spindle from said release configuration to said lock configuration of the bayonet fitting between the spindle seat and the electromechanical actuator. - the brake backplate of the drum brake, having a rear surface opposite to a front surface configured to be facing a brake drum when the brake backplate is mounted on a motor vehicle, wherein the rear surface of the brake backplate includes a support base configured to receive a pull spindle of the electromechanical actuator, - a supporting bracket including at least one coupling plate (205, 210), configured to be attached to the rear surface of the brake backplate, and an actuator mounting surface configured to be coupled to and support the electromechanical actuator, wherein the actuator mounting surface includes a spindle seat, configured to receive the pull spindle of the electromechanical actuator, the actuator mounting surface of the supporting bracket further includes a pin lock seat, configured to receive and lock an engagement pin of the electromechanical actuator, the rear surface of the brake backplate is provided with at least one first mechanical member and said at least one coupling plate (205, 210) is provided with respective at least one second mechanical member, wherein said at least one first mechanical member and said respective at least one second mechanical member are configured to engagedly slidably interact with each other, and wherein the spindle seat is configured to be connected to the electromechanical actuator through a bayonet fitting including a release configuration and a lock configuration, and the pin lock seat is configured to lock the engagement pin when the pull spindle is inserted into the spindle seat and the electromechanical actuator is rotated about a longitudinal axis of the pull spindle from said release configuration to said lock configuration of the bayonet fitting between the spindle seat and the electromechanical actuator.