Crowds inspect planes at Hendon on Empire Day . Large crowds watched the Empire Air Day display at Hendon Aerodrome , the 11th London Regiment ( The Finsbury Rifles 0 , which now comprises the 170th and 171s Anto Aircraft batteries co - operated with the Royal Air Force in the display . Photo shows , a Vickers Type 264 Valentia passing over an anti aircraft gun of the Royal Artillery . 23 April 1936