Spotted last night on a 50mph A-road at 1:10am, ninja cyclist in the opposite carriageway. I did see him, but only because of his pedal reflectors. There was an adjacent off-road path, but it goes through the bushes a bit so probably he was staying on the road because he couldn't see. 
I didn't do anything, but feel I probably should have stopped or called the police or something.

I didn't do anything, but feel I probably should have stopped or called the police or something.