The destroyer sent to intercept the SS Viking is the HMS Echo (H23). This was one of 9 E class destroyers of the Royal Navy. She was launched in 1934. During the Second World War she sank a U boat in 1943 and was transferred to the Greek Navy in 1944.
Several scenes were filmed at Brooklands - the Clubhouse and the banking are clearly visible. When the Ministry Dragon Rapide comes into land a Wellington is just visible in the background. The test plane appears to be an Airspped Oxford; other planes were Tiger Moths and Gypsy Moths, and possibly a Bristol Fighter (just the engine and propeller are seen).