The ébauche of the present movement was made circa 1935 in the Ecole d'Horlogerie de la Vallée de Joux, watchmaking school of Switzerland's Vallée de Joux, finished and encased circa 1985. The tourbillon carriage is based on Auguste Grether's second type and its unusual shape (see Reinhard Meis Das Tourbillon, p. 43, Z49 "Grether 2"). For other examples of tourbillon movements made by the Ecole d'Horlogerie de la Vallée de Joux, including one supplied to Breguet, see op.cit pp. 148, 187, 188 and 189.
The impressive case of highest quality was made by the famous casemaker Jean-Pierre Hagmann of Geneva, his hallmark JPH stamped on the inside of the hinged case back.
Originally trained as a jeweller, Jean-Pierre Hagmann set up his own company in 1984, specializing in the manufacture of custom-made high quality watch cases. He worked for several of the world's most famous watch manufactures, notably Patek Philippe, to whom he supplied amongst others cases for references 3974, 3979 and 5029, all models of the firm's "Grand Complication" series.
Today Jean-Pierre Hagmann is the point of reference for case making and without doubt the most skilled artisan in this field.