This instrument is an exceptional one, without equal both for its history and its conception. In 1907 it was installed in the castle of Ilbarritz, Bidart, near Biarritz in the French Basque Country. The castle belonged to the Baron of l´Espée, a millionaire music lover and eccentric who played concerts and improvisations (mostly on Wagnerian themes) on this instrument, inviting high society of Biarritz and Paris to the soirees.

It was devised as a drawing room organ. It had three manuals, each with 62 stops, 26 of which are integrated into a small manual located underneath the first, containing sound effects such as timpani, triangle, gong, castanets, etc. Most of this organ (two manuals) was sold in 1920 to the parish church of el Salvador in Usurbil, by organmakers Fernand Prince and Gauziède being responsible for its transfer and adaptation to a church organ.

Currently, the Usurbil organ has three manuals and one pedalboard that provide an exceptional range of notes, the first providing 64 notes (A0 to C6) and the last, 35 (A0 to G3). After the restoration in 2010 by the French firm, DLFO, directed by Dénis Lacorre, the organ has a total of 46 stops. Moreover, this organ has an extraordinary Cavaillé-Coll combination system invented by Pierre Veerkamp, that enables the pre-programming of five different stops, an exceptional and admirable phenomenon of which only one other exists (in France).