In "Four Centuries of Liege Gunmaking," Claude Gaier mentions a Liege gun and hardware dealer named Lepage as being listed in a commercial directory of 1808. This is apparently not the same LePage we usually think of... a famous Parisian gunmaker. Without pictures this sounds like a Belgian export gun for sale to Americans and intended to take advantage of the similarity of the name with the more famous French gunmakers.
Also, regarding the Belgian proofs - Belgium allowed its gunmakers to mark any name they wanted on their products but they did insist on proof... the traditional Liege mark was instituted by a decree of the French government dated December 10, 1810. At the time, Belgium was incorporated into the French empire and most of its prodigious arms making efforts went to making arms for the French and their allies. Its ports were also blockaded by the Royal Navy, so the likelihood of Belgian civilian arms reaching America between 1810 and 1813 is nil. From 1813 to to the fall of Napoleon the manufacture of civilian arms was prohibited altogether. Very few, if any civilian arms were made until the end of the Napoleonic wars, so effectively the earliest date we can expect to see that mark on an export gun is 1815/16.
"ELG" is a pure Belgian mark - having nothing to do with England. It really should be read "LEG" for "Liege."