tub-man

from The Collaborative International Dictionary of English v.0.48

Tubman \Tub"man\, n.; pl. {Tubmen}. (Eng. Law)
   One of the two most experienced barristers in the Court of
   Exchequer. Cf. {Postman}, 2.
   [1913 Webster]

from Bouvier's Law Dictionary, Revised 6th Ed (1856)

TUB-MAN, Eng. law. A barrister who has a pre-audience in the Exchequer, and 
also one who has a particular place in court, is so called.

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