Slightly different environment, but my dad was a service engineer in the 1960-1980s mainly working on coin counting equipment. His workwear for customer sites was a white coat over his suit. That was fairly normal back then so probably kept to traditions in industry. I've nothing to add about the hat though.

I've not got a photo of him at work, but this is him wearing one of his old & dirty coats after he retired.

https://www.flickr.com/photos/stevecargill/52576937191/