I used to walk home down a narrow alley by the river which had a bad reputation as the site of various sexual assaults. I’m 6' 3", and 117lb, and I sometimes found myself walking behind women on their own. It kind of brought home to me; o fhow scary it must be to find yourself in a place like that, alone with an enormous bloke walking behind you. The problem is, it’s kind of hard to broadcast your harmlessness without looking kooky. Saying ‘Good Evening’ didn’t work; I’ve got a baritone voice, and the alley echoes, so I sounded like Darth freaking Vader. Whistling or humming doesn’t work; given the context it just feels like a slasher movie waiting to happen. In the end, I just took to wearing my cycling hi-vis; you’re a lot less scary when you can be clearly seen.