Interesting observation, John; I haven't seen one like that.
I don't think it is Daphnis nerii; I think it is Acherontia atropos (death's head hawk moth), which is rarer.
Even in its brown phase, Daphnis nerii shows the pseudo eye spot, and it doesn't have the diagonal lines on the sides.
Here's an Acherontia atropos larva in its more usual colours.
I found it wandering up my driveway a couple of weeks ago.
It is as big as my index finger.
I wonder if I will ever see the very impressive adult...