The photos were taken at the April 1964 Pukekohe meeting and this is the entry list for the over 1501cc sports cars at that event.
The incident was probably this one described in Motorman.
"A further incident at the Elbow occurred during a sports-racing handicap event when Sheffield's Dart spun and was narrowly missed by Thomasen while it was airborne."
The spin was also mentioned in the ACC Bulletin report.