Hi Samantha, there was indeed a Harrietsham Aerodrome that was part of the London Air Defense Area. But I think that the airfield was located about three miles northeast of Harrietsham, at Frinsted. It was in service from December 1916 through the end of the war and disused thereafter. During the war, it was the HQ of No. 53 Wing which was formed March 11, 1918 and controlled the operations of Nos. 50, 112 and 143 Squadrons.
The Gotha was brought down in a field between Frinsted and Harrietsham, an area that still looks very rural. Here's a picture from Google Earth of the field at Frinsted today.
