In reading Lifting the Latch, which is the story of Mont Abbott’s work on the land in Oxfordshire in the first half of the 20th century. The phrase “Brusher were the yedsirag over all the steam ploughs” appears in it. The glossary defines yedsirag as meaning head man, foreman.
The book has another example:
"Chisel were the only true ringer among us so we made him yedsirag, Captain of the Tower."
Lifting the Latch: a Life on the Land, Based on the Life of Mont Abbott of Enstone, Oxfordshire, by Sheila Stewart, 1987.
"Yedsirag" is not recorded well and because most appearances are phonetic transcriptions of local dialect speech. Researchers for the English Dialect Dictionary of the late nineteenth century recorded it in a variety of spellings across a swathe of central England. Here’s another example:
"He was gooin’ orderin’ an’ mesterin’ abait, just for aw the world as if he’d bin top-sawyer an’ yed-sirag o’ the lot."
The Folk-Speech of South Cheshire, by Thomas Darlington, 1887. Mesterin’: acting like a master, an employer.
“This strange word Sir-Rag is common in the Midland Counties, and has been for very many years. I knew it, and very often heard it, when a boy. The chief of a band of servants or workers, a foreman or overseer, or any one in authority over others, is the “sir-rag.” Sometimes he or she is the “head sir-rag.”
Thomas Ratcliffe of Worksop, writing in Notes and Queries, 15 Aug. 1891.
And now an explanation as to how "Yedsirag" may have found its way into the Australian and new Zealand lexicon.
There is a local expression in Australia and New Zealand that looks hauntingly similar: head serang, or head sherang, for a boss or a person in charge - usually in an agricultural setting where paid labor was employed and needed supersvision - yet, again, in a gently mocking or ironic way.
It has a very different origin, from the Anglo-Indian serang (the spelling that appears in the Macquarie Dictionary), originally from the Persian sarhang, commander. Yule and Burnell defined it in Hobson-Jobson, their huge compilation of Anglo-Indian expressions of 1886, as “a native boatswain or chief of a lascar crew; the skipper of a small native vessel.”
However, the similarity to the older British expression, which would certainly have been known to nineteenth-century migrants, is so striking that it must surely be linked and presumably accounts for the addition of head to the Anglo-Indian word.
"I were on the last lap of the day, longing for me tea and our Mam’s roly-poly, when ‘Brusher’ Becket came into the field waving a telegram. 'Brusher' were the yedsirag over all the steam-ploughs."
So there you are - "Yedsirag" transformed from 19th century English use to "Head Serang/Head Sherang" in the antipodes of the 20th century!