Ah, yes: I was born and bred in Monifieth: now a sprawling suburbia dormitory town of Dundee. Then (late 1950's/early 1960's) it was a small seaside village with three (yes three!) foundries and a carpet factory. Population something under 3,000.

The bummer was the horn - I think probably steam driven, but maybe electric - which signalled the end of the work shifts at the factories. 12.00 and 17.00 (or 5 o'clock as we used to say in our quaint way). And then the workers would stream out. It was clearly audible all over town: well it had to be to be audible inside the foundry!

A totally different town: days of the eleven-plus where those who didn't make the cut left school at fifteen and served an apprenticeship and/or worked at one of the local industries, which was within walking distance of home. I don;t know, but my impression now is that unemployment levels were low.

I don't know how widespread the word was: certainly all over Dundee. It's basically onomatopoeic, and never had any rude connotations to my innocent mind.

The use of the word "bummer" for a negative event is relatively recent, at least in the UK. I guess it was the 70's when I first became aware of that use of the word.