Yes, once upon a time Ken Russell was in control and was actually able to turn out a beautiful and sensitive film bio--how perfectly appropriate here, since the subject was composer Frederic Delius.
Max Adrian was superb and SO believable. I once saw a TV interview with Russell who related that, while filming this picture at the actual site of Delius' house at Grez-sur-Loing, Eric Fenby himself showed up to observe the day's shooting, and broke down into tears as he beheld young Christopher Gable playing FENBY HIMSELF, seated at the side of Delius in his wheelchair, taking down musical dictation. Imagine the overwhelmingly bittersweet shock of that event for Fenby!
Sometime in the early '80's, I met Eric Fenby in Chicago; he was here as part of a Delius Choral Festival. The Film "Song of Summer" was screened--but just barely! The BBC, at the last minute, decided NOT to send the print to Chicago and it was only through a combination of pleading and good luck that they finally agreed and sent it. I spoke with Fenby about the filming, but he seemed to wish to avoid his deeper feelings about it.
Prior to that, I had seen the film in May of 1971 on the local Chicago PBS station. To my knowledge, it is not available in any format, and probably never will be. A great shame.