I have W.C. Green patent number 2716 of Sept. 3 1868. The British Shotgun, Volume One 1850 to 1870 by I. M. Crudgington and D.J. Baker. page 223. it states that,

"The hammerless gun he designed was cocked and opened by a push forward under lever, which also was the trigger guard. In both actions the lockwork is built on the trigger plate."