Buy the latest issue of "Backwoodsman", the editor has an article on his .44-40 Belgian S&W copy, it sounds identical to this one.
For what it is worth, I have seen several SPANISH copies of Webley or S&W revolvers that were accepted as British substitute standard in WWI, but never any Belgian copies. Those copies were all .455's, however.
You might recall that Belgium was overrun by the Huns during WWI, which would rather preclude any substitute standard revolvers originating there.
P.S. The Belgians obviously DID make copies of the various Webleys and S&W's, of that there is no doubt. I just have my doubts as to whether any were accepted as substitutes by the Brits.