Can anyone, especially our British colleagues, provide identification of the touchmark "HM" or manufacturer of a late eighteenth - early nineteenth century, brass, shoe buckle?

A line drawing of the buckle is provided at the URL below. The buckle was salvaged from the Deloeuil house and blacksmith shop (1789-1867)excavations in 1988, and has remained in storage since that time at the Monroe County Historical Museum in Monroe, Michigan, USA. A photo of this artifact is currently being looked for in the site collection. I suspect the buckle is a product of the Birmingham brass industry during the turn of the eighteenth century. Is there a registry of touchmarks or manufacturers of brass buckles from Birmingham, Great Britain, during the late eighteenth - early nineteenth century period?

http://s145.photobucket.com/user/Pat_Tucker/media/20Mr229/Clothing20Mr229BuckleShoeBrassHM28N60-65ETestTrench_zps33473158.jpg.html

Pat Tucker
Firelands Archaeological Research Center
Amherst, Ohio, USA