During my career the only managers I could trust were the managers who could have some understanding of the work I was meant to do.

It was alright if they didn't knew as much as I did. They just needed to know enough that I could have a meaningful conversation about what was going on in the projects they were trying to manage.

Maybe I’m being too specific in my interpretation of GP’s use of the word “understanding”

I interpreted it to be an understanding derived from experience from having done the job, but now after your message I could see it meaning an understanding of what the output should be, not necessarily how that output was produced.

Good leaders always lead from the front. There's nothing special about this "knowledge work". It's the same as any other industrial job in this respect. A good foreman can do everyone's job better than them and knows how to keep the higher ups off your back. They're someone you look up to professionally. There's no way you can look up to someone who can't do the job well.