Hi Nigel,
This race was also known as the "England-Australia Commemorative Air Race" flown in commemoration of the 50th anniversary of the Smith brothers' flight in Vickers Vimy G-EAOU.
The race started 18 Dec 1969 and finished 4 Jan 1970, and was won by W. J. Bright and F. L. Buxton in a BN Islander G-AXUD.
These photos may help (you can see enlarged versions by clicking on thumbnails), and show a couple of Piper singles in one of the photos:
http://www.pictureaustralia.org/apps...ld&mode=search
I have posted a request on OzSpotters discussion forum, as someone here in Australia should at least have some photos.
Regards,
David Eyre
Perth, Western Australia.