I have just found a box of old harness decorations. They come in many forms : simple solid badges, some interlocking monograms or ciphers and some depicting parts of crests or coats of arms.

Harness Insignia

This decoration features a bloodhound. The French motto translates as “Search & you will find”, rather a nice pun.

They were not solely decorative. If we think back to a time when several guests, each with their own carriage & up to four sets of harness, might have visited a country house – the potential for confusion between sets of harness would have been enormous. So, these decorations served as rather elegant identification tags.

“Templa Quam Dilecta” translates as “How beautiful are your temples”, it is a pun on the family name Temple and is associated with Stowe School and Archbishop Temple’s School

Motto from harness

They could be made of brass or a white metal, some were hollow & lead-filled, some silver plated. Generally they had pins on their reverse sides which would be inserted into the leather.

 

A muzzled dog – rather a strange emblem

Harness decoration

Back of harness decoration

There are more at http://www.sportingcollection.com/lorinery/ciphers/harnessornaments.html