Hmmm...

I "Googled" <40 years a ganger and I've never sacked a man> ... and all the came up was this thread - and Jim's link to a "blog"!

It does look like this something out of the vast and wide-ranging history of (largely Irish ...?) army of "navvies" that built just about everything we depend(ed) on in transport ... before that left the ground / road / rails / river / canal / ocean behind (or below!).

I'll keep an eye on this, but I am bereft of bright and useful notions.

Regard(les)s,

Bob