Watched a Chipmunk demonstrating the toilet roll trick at Old Warden recently. Just as the commentator was going on about 'ad-lib aeros' the engine stopped, while going vertically upwards!
There followed an excellent demo of in-flight restart proceedure, nose over, what seemed like VNE, and off it went again but I fancied the flying seemed a little shaky after that..
(I am sure he had enough momentum for a circuit and landing anyway)