I am not convinced that panniers do work on a Bromton with the standard rack without clearance issues. Is there a real need for panniers that use the Mezzo clip system, most I have seen use a clip that fits over the side rails of the rack.
How about this.
Taken for this review of a very early Mezzo.
http://www.velovision.com/showStory.php?storynum=1240