djpil,
The "civilization" of ex-RAF Chipmunks involved extensive minor modifications, mostly nonsense, and the civilian powers that be just throwing their weight around. Amongst other things, apparently MoD/RAF wiring standards were not adequate for the rigors of civil use. One nonsense was the Ground/Flight switch had to be turned upside down.
Some of those involved became 10 Pound poms and joined DCA in the old Henty House.. We know the rest of that story.
DCA accepted ex- RAF Chipmunks basically as was, except for the anti-spin strakes. Indeed, the absence of a "manufacturer's AFM" only became evident in 1998, when the CASRs Part 21-35 were enacted, rendering the Australian "DCA approved" manual obsolete.
Hence the deal with DH Support to plug the bureaucratic gap.
Tootle pip!!