From Page 107
“Inspecting an A&D made by Westley Richards, or another gunmaker, will reveal the action to have the rectangular box-like appearance characteristic of this type of gun. W. W. Greener made A&D actions which were box-like and looked the same as the classic A&D shape since this was the easiest to make. But Greener, and an increasing number of his customers, liked the shape, feel and handy nature of the Facile Princeps which has a narrow shaped part of the action where it joins the fore-end. So WW modified the appearance of some of his A&D models to look the same as Facile Princeps guns to improve their shape and feel.
So, when looking at the Facile Princeps and Anson & Deeley guns made by W W Greener there may be no visual difference in their external appearance and this includes both ejector and non-ejector models.”
Graham G then goes on to talk about removal of the cover plate and describe the differences – in short, FP has tumbler forearms turned inwards and A&D has protruding cocking levers.