As promised, I made a call to the factory this afternoon and spoke to one of the shop floor mechanics who deal with wheel fitment. And this is what he told me:
Put your supplied wheel nut spanner in a vice and bend it twice to introduce a crank at the nut end of the spanner.
Grease the threads with copper slip before reassembly.
Fit the retaining nut by hand and hand tighten.
Tighten the nut with the spanner until no longer able to turn the spanner.
Strike the spanner shank until a change in tone is audible. At this point, the nut is as tight as required .
I was informed that they have NEVER used torque wrenches for wheel nut fitment and use the ‘good old fashioned spanner and mallet method’.
So there we go, a typical ‘Morganism’! There we are, a proper noun develops to become a verb!
I will attempt to measure the torque whilst undoing all the wheel nuts and see if I can establish a mean torque level. Further reporting at a later date.
