Thanks for that link, Charlotte.
Again, its appearance rings bells in what passes for my memory but I have no knowledge of whether the Nariel instrument was diatonic or not, as I never got my hands on it. It wouldn't surprise me to find that the Klippel's one was diatonic, as the Nariel area as well as its music, was (in the 1960s) dominated by Hohner single row button accordions and melodeons, all in C. Keith Klippel (Con & Beat's nephew) is getting on but still plays his Lachenal 20 button C/G concertina in the Nariel dances every year.

As an aside, The Klippel family got a junior band going and the LP of the Nariel dance music has, as its cover, about 20 kids sitting along the trunk of a fallen eucalypt, all with accordions on their knees. Two of those kids were Ray and Ian Simpson, sproglets of Neville and Maureen, who lived over the Creek from Con and Beat and who played with them in the Nariel Band. These days, Ray and Ian both play anglos rather well and Ian makes anglos and very good timber penny whistles.

Cheers, Rowan (who is about to commence the working day)