In 1956, long before cycle helmets were thought off, my dad's younger brother was cycling to work and was knocked off his bike by a woman who opened her car door without looking. He fell onto his head and died three days later. He was thirty two and had two young children.
Had helmets been worn in those days I'm sure he would have stood a stronger chance of survival.
This kind of thing can still happen today and, indeed it does. Although it is an offence under the Road Traffic Act it is still something I see drivers do quite regularly to the danger of pedestrians as well as cyclists.
I taught cycling proficiency to year 6 children for 15 years and it was a strict rule. No cycle helmet-no course.
Whether or not it becomes compulsory, I'm all for it and wear my cycle helmet whenever I'm out on my bike.