The Kilnsea sound mirror got a mention on the BBC website:

… One legacy of the raids is the sound mirror, which still stands in a field just outside the village.

The large concave concrete dish acted as a primitive radar, amplifying engine sounds from distant Zeppelins so they could be heard by an operator, who would then send an air-raid warning inland by radio.

Source: World War One: Spurn Point’s military relics at sea’s mercy, 28 February 2014

(note that despite what the article says, the Spurn railway was standard gauge)