Seeing the Bus again after some time, it occurred to me that LP had been borrowing ideas again, as we has seen with the smaller space vehicle range, shown below, which were based on a German Panzer IV tank chassis.
Looking at the wheel arrangement, I recalled that the overlapping idler wheels had been lifted from the panzer division once more, in the form of the fearsome Tiger tank.
So the rocket launcher had been ‘borrowed’ from the Lone Star diecast Modern Army series vehicles and the chassis for the two vehicles had a military origin as well.