Auguste Larriu was a lawyer who also became organist of the ancient (and quite large) Église Sainte-Croix (Holy Cross Church) of his native city of Oloron, in the deep southwest of France, in 1868. Apparently he held the post for the rest of his life. His oeuvre as composer comprises organ music, but also at least one opéra-comique (you believe it when you hear this piece). The children in the postcard -- showing the Sainte-Croix bell tower and the door of the north transept -- may well have heard him play. When he took over his post as organist Sainte-Croix still had an organ going back to 1673 but modified in 1780 and 1856. Following the example of the Église Notre-Dame and Oloron cathedral, which acquired new organs (both of them by Aristide Cavaillé-Coll) in 1851 and 1870 respectively, Sainte-Croix also received a new organ, made by Michel Roger and which Larriu inaugurated on 8 April 1886. Sadly, this instrument (26 / II + P) was removed and apparently destroyed when the church was restored in 1960; it has not been replaced.
The instrument heard here, the organ of the Old Independent Church in Haverhill, Suffolk, built by James Jepson Binns in 1901, is not French but at least contemporary with the piece.