Thom’s Directory for 1850 [Thom’s Irish Almanac and Official Directory, with the Post Office Dublin City and County Directory, for the year 1850 Alexander Thom, Dublin 1850] lists the more important employees of the Grand Canal Company:
Secretary John M’Mullen esq
Bankers D La Touche & Co esqrs
Superintendent of Trade and Passage Boats Samuel Healy esq
Land Agent and Paymaster Thos J Thornhill esq
Book-keeper Francis Bray esq
Collectors: at James’s-street Richard Davis esq, at First Lock Mr Thomas M’Ghee
Accountant Mr Thomas Brady
Storekeeper Mr William Talbot
Broker Mr William Warham.
So the Collector at James’s Street, like all those listed before him, was an esquire but his colleague at First Lock, like all those listed after him, was a mere mister.
Wikipedia’s nineteenth-century definitions of “esquire” are of interest. The Grand Canal Company might have sung with the Gorbals Die-Hards …
Class-conscious are we, and class-conscious wull be
… but perhaps not the next line
Till our fit’s on the neck of the Boorjoyzee.
Irish waterways history 