The first half of Stokowski's 90th Birthday concert with the London Symphony in 1972 was televised and has now popped up on YouTube. Shortly after the start of the "Mastersingers" Prelude, the first violins are seen in "free bowing" mode, as per Stokowski's invariable instructions. The commentator refers to the extreme sonority of the "Stokowski Sound" and as this was achieved by free bowing, I wonder why more conductors haven't taken the idea up ...
https://www.youtube.com/watch?v=MARtrTRSv7w&t=835s