Reading the SMH report I think that Harley and Neville have effectively let the cat out of the bag and confirmed it:
Col died in the accident this morning. The two people seen swimming at the wreckage were two of Pay's engineers, observing the trials from a boat.
Pay was alone in the aircraft, VH-LIS.
I am only one of the many many pilots who owe their career to Pay. Like all at Scone and many further afield, lost for words.