Random Highway Code Testing

Should the traffic police have the power to stop a motorists and require them to take a highway code test. If they fail to answer 4 out of 5 question they have 6 months to take/retake the theory test or they revert to provisional.

One question could be:

If you see a white circular sign with a red border and the number 30 in the middle, what is the maximum speed you can drive at:-

A 30mph
B: 35mph
C: 30mph+10%+2mph
D: I pay road tax
E: It was the cyclists fault
F: I am an above average driver so I drive according to the conditions.