A man wearing bowler hat reading a newspaper is seen leaning leisurely against a car. Another person comes from behind and starts hitting the poor man on the head with an iron bar. He does not react at all, still reads his paper. The third man appears looking puzzled. The man takes his hat of and shows it to the other two. They take the hat and examine it.
This bowler is specially designed to protect cashiers and guards from violent attacks. Its inventor is John Fisher from Farnham, Surrey, the man who wore it earlier. The bowler most probably has a curved steel piece fitted inside the hat. The man who was previously reading the paper takes the bowler and places it in front of the car wheel for another demonstration. Another man starts the car and drives over the bowler which, instead of being squashed, preserves its shape.
Another ingenuus device comes in the shape of a briefcase called "Arrestor". Mr Fisher walks towards the other two men with a briefcase in his hand. Another man 'steals' the briefcase and finds himself trapped. The bag's handle clamps down gripping his fingers, alarm starts screaming and three 12 feet long metal bars 'unfold' from the bag in manner of a car antenna!?
He tries to free his hand but it is impossible - at least until Mr Fisher unlocks the bag. Still, what happens to a thief who does not have a key? - asks a voiceover. Another man takes a bag with the 'antennas' sticking out and demonstrates the impossibility to get through a door with it. He tries to get the bag through the door but fails.
Note: The film appears to have a very abrupt end, as if it was cut in the middle of an action. Greatly amusing 'Arrestor' booklet and using instructions in file.