Perusing a 1963 Ordnance Survey map, I noticed a long-gone bit of railway which I’d never noticed before, running off the Middlesbrough – Saltburn line at Ryehill Farm between Redcar and Marske. A bit of Googling finds references to Marske aerodrome, complete with photos of the sound mirror from 1983.
Plus some more pictures of the Marske mirror
My photos of the Marske mirror