Five years ago whilst barbel fishing a very enclosed, no way out but jump into the river swim on a west London river, I was visited by a mid fifties fruit-loop. I could see trouble coming as soon as his conversation went from trying-too-hard "I go fishing" affable, to faltering, to borderline incoherence, and quietly opened the Buck lock-knife I had in my jacket pocket...
Then a walker came along, a man in his late 60s whom I recognized as a regular fisher of the river from years and years ago. He stopped, then sensing I was in trouble, shouldered his way into the swim, stood beside me and began engaging me in "How are you doing?" fishing talk. The fruit-loop stumbled off within thirty seconds. Lucky for me. Lucky for him too - I'd've gutted him.