I'll wade in a bit -- the Sept. 5, 1843 Richard Clyburn "design" patent & provisions of the pertinent British patent laws was noted on pg. 4 of the June 2010 MVWC Newsletter. That bit was copied from "The London Journal of Arts & Sciences" which google had digitized from Oxford University's Library collection.
The CLYBURN design was kept in production for a long, long time -- the lettering style on the example pictured looks 1920-ish (sorta like the lettering on the WAKEFIELD WIZARD and other 1920s U.S. wrenches).
