I'm not sure there would have been anyone in the vehicle. While some launchers have an armoured compartment for the detachment, this vehicle looks pretty spartan. Could be though. If not, the detachment is in a remote firing point where it initiates the launch sequence fires the SOB on order.
Clearly the propellant had been made by the lowest bidder, and/or it had deteriorated badly in storage.
In the mid-sixties 1 SSM Bty had a rocket blow a seal and vent thrust in both directions. It apparently tried to run up the rail on the launcher, but the counter-thrust would force it back. After several seconds of back and forth, it got far enough to pass the trip for the spin rockets which ignited and it rolled off the launcher to lie beside it going through its death throes like Godzilla in an epic Japanese horror flick. Those who saw it said it was really spectacular, or as sectacular a sight as one could see from the prone position.