I'll never forget the time that I visited a classic car show and amongst the gleaming, highly polished, cars a Humber Pig armoured personnel carrier had arrived which I was quite pleased about because I have always thought them an interesting vehicle. The Humber Pig had parked in front of a nicely restored sports car with a reasonable distance between the 2 vehicles.
At any classic car event you often get someone who decides that they want to go home before the show has really finished and on this occasion it was the owner of the Humber Pig. He started the Humber's engine which caught everyone's attention and then to everyone's surprise, instead of driving forward, ever so slowly, he began to reverse. Everyone was expecting the driver to then stop reversing and start driving forward, not least the sports car owner having a "nice relaxing siesta" in his car at the time. One could tell that he was getting nervous as he cautiously reversed his car back as much as he could within the confines of the other vehicles parked around him, yet the Humber kept coming.
People on the show field began shouting "STOP" yet the Humber kept reversing at crawler pace, directly for the sports car, with the Humber driver appearing to be oblivious to what was about to happen. With millimetres to spare someone had managed to climb onto the driver's door step and shout "STOP" directly" into the driver's ear.
As there was no harm done it did have a slightly amusing side to it, watching it unfold, but I wouldn't like to speculate as to the condition of the sports car driver's underwear.
An aside: I believe that in Northern Ireland service they had a relatively low speed limit imposed on them for safety reasons except in emergencies. I did know what the speed limit was but I forget off the top of my head. I expect that someone will confirm what it was?