After a short cross-country flight to Membury the aircraft joined the circuit downwind to land on grass Runway 13. On final approach the pilot misidentified the runway threshold and confused it with the Runway 17/35 intersection. The pilot now had a significantly reduced landing distance available (LDA). After touchdown she applied maximum braking to stop the aircraft. As a result the aircraft tipped forward on its nose, causing the landing gear to collapse and bringing the aircraft to a stop.