No I really don't need a cycle helmet... or do I?

On the one hand, it's a bit health and safety gone mad. I've been cycling for half a century, on and off. Never had a helmet, don't need one now, and a peaked cap keeps the sun out of my eyes better.

On the other hand, I've been chatting to a couple of cyclists my age (60s) recently who are horrified I don't have one and recommend I should get one pronto. And "nobody thought seat belts were necessary until they became compulsory, but who would think of not wearing one now?".

Any thoughts?