According to Burke’s General Armory, this is the stamp of the antiquarian Philip Hills of Colne Park, Essex.  

In 1762 Michael Hills (d. 1786) created Colne Park on the site of the former manor house.  Michael built a new house which he transferred to his son M. R. Hills (d. 1790), who passed the estate to Philip Hills, grandson of the historian Philip Morant, on condition that he take the surname Hills. Philip (d. 1830) was succeeded by his son Robert Hills (d. 1876) and then by Robert's daughter Mary Frances (d. 1884) and her husband J. F. Reeve.

Philip Hills erected a Greek Ionic column at Colne Park, designed by Sir John Soane, topped by a copper cinerary urn.