Thanks to Susan P. for sending these pictures. The clarinet is a French stencil clarinet from the 1960s. At least two different logos were produced. Possible makers are Malerne and A. Fontaine.

Another Trianon clarinet was found on eBay. It sold for $39 in bad condition. Note the different logo. The serial number was A26856. 

Evidently the name Trianon is French.

Either of two small palaces in the great park at Versailles in France. The larger was built by Louis XIV in 1687; the smaller, built by Louis XV 1762-8, was used first by his mistress Madame du Barry (1743–93) and afterwards by Marie Antoinette.