Debussy composed this work in 1915 as part of a sonata collection for different instruments. He referred to it as a sonata, but because the combination of instruments was so balanced, it became popular and referred to as trio. Debussy at first wrote it for hobo instead of viola, but he liked the combination with a bowed instrument better.
The Robles Trio is a British trio formed by and around Spanish harpist Marisa Robles, together with her husband playing flute. They started in 1969, but this record is all I can find of them. They performed a couple of time on BBC radio and were a regular at a festival in Stevenage.
I’m checking this, because I’m really impressed with this recording. It is performed in an open, vibrant way, and the recording is very good, especially given that it was made in 1970. For most recordings this is a bit of a challenging time. A shame it is not on Spotify.