Dr. J. H. Walsh, “Stonehenge”, Editor of The Field was highly influential in the second half of the 19th Century.
This is Bland’s variation on his “Gun of the Future” (a misnomer if there ever was one) he patented No. 5106 of 1878, a hammerless version of his earlier 516 of 1866.
Edwinson Green made and sold a few, Greener made at least one and so did Bland.
See Crudgington and Baker, The British Shotgun Vol. 2 pp.172-3.
I suspect the makers who adopted it anticipated that they would get a good write up in The Field.