I wear a standard Bell bike helmet when riding my road bikes.
That said, I can't abide by the idea of wearing a helmet on my English 3. It just seems like wearing a bomb suit while driving a car. There's safety, and there's style. With an English 3 speed or roadster, I can't see going fast enough to actually need a helmet.
Then again, I've never actually fallen where I've needed a helmet and, God willing, I'll never find myself in that situation. I did fall when hitting a crack in the pavement when I couldn't get my foot out of the clip fast enough. Cracked a bone in my ankle and still (two years later) get aches and pains in it when walking for too long.