Ok - it's not a Benz.
It's the PV. Cruising along comfortably and then a loss of power traced to the exploding distributor cap - see the picture below. A quick call to Paradise and the car is again mobile with new rotor button and cap. The old one had been checked in the last service a week ago and tested OK on the analyser and looked OK with a visual inspection.
The question is why did this happen? Yes, there is a vacuum advance and I have heard of older Holdens having this problem when...