I let you believe that I am one of the nation's top geneticists, when actually I am a moderately successful scientist who is now coasting on past research, doing the odd bit of examining or consultancy. I haven't been at the coalface for years.
From the novel, Apple Tree Yard. By Louise Doughty
The Free Dictionary defines the British and Australian idiom at the coalface as: someone who is at the coalface is doing the work involved in a job, not talking about it, planning it, or controlling it.
The Phrase Finder explains
it is a way of saying that the person is 'in touch' and appreciates the actualities of the business rather than being a 'bean-counter' (accountant) a 'paper pusher' (administrator) or a 'fat-cat' (overpaid manager).
obviously the original 'coal-face' is a mining term to describe an underground worker that actually cuts the coal from the rock - but the sense of direct involvement with the core of the business is the important element, rather than it being dangerous or dirty.
Considering today's high-technology age, I think it sounds old-fashioned and outdated. Is there a more modern equivalent?
From the comments it seems that many American English speakers are unfamiliar with the British idiom. Which AmEng expression or idiom could replace "at the coalface" in the passage quoted above?