If possible, look at the name and absolutely know that it is not a T but an E.
Ernest Dumoulin followed his famous father, Henri, in the building of very,very fine shotguns. Both side locks and box locks.
Ernest started in the very early 1930s and that time frame fits the gun under discussion.
His best guns were/are the equal of a London best although do not bring that price today.
Best,
John

Humble member of the League of Extraodinary Gentlemen (LEG). Joined 14 March, 2006. Member #1.