Named after Thornhill, the residence of Dr Henry Norman Barnett on Upper Newtownards Road. He was a specialist in ear, nose and throat medicine. Further biographical details are given in Knock, Knock... who was there? by Keith Haines (2014), pp. 58-66.
Resolved that the following street names be approved…Thornhill Park and Thornhill Drive for new streets on the property of Mr Joseph McMaster off Upper Newtownards Road. (8th May 1934).