Martin,
My missis and I were threatend once by another window cleaner and his side kick - face to face.
It wasn't very nice. Being a Geordie - I just wanted to stick it all over them. I would've received a good kicking though. My missis is only 5' 1".
Anyway, we phoned the coppers instead and were visited within three hours.
This is what the policeman said:
It's good we reported the incident, because if any other incidents occur, then it can be classed as 'harrasment' (two or more incidents) and action can be taken.
He could speak to the 'threatener' and warn them it's been reported. This could either settle the incident or inflame the incident. We decided against this.
Anyway to cut a long story short - he keeps out of our way and we keep out of his. Nothing has happened since (but I'd still love to give him a digging).
So my advice is:
Phone the police and log the incident.
Forget about it. He just sounds like a drunken toss pot who wouldn't say boo to a goose in the cold sober light of day.
Remember that 99% of window cleaners are good, hardworking guys. I cleaned a house side by side another 'rival' window cleaner today and we enjoyed talking shop.
'Shop talk' tends to bore non window cleaners. ("What do you use - Fairy? I find it wrecks my hands, etc...")
Remember to pass on customers to them, whom you don't want - once you get to know where they work. Every time you meet a new window cleaner, introduce yourself, ask for their phone number (if they're decent - they'll ask for yous). Network with them.
DON'T DARE BUY THOSE CUSTOMERS OFF HIM. Window cleaners sell stuff off they don't want. Why doesn't he want them? Not only that - he doesn't sound like the sort of guy you'd want to do business with.