Believe it or not, BBC TV actually did a short Kenny Wheeler documentary which included footage taken at the recording session (CTS, Wembley I think). It was rebroadcast around 2005.
The Wheeler 75th and 80th Birthday Big Bands had a similarly eclectic mixture of artists and styles - those bands were full of his friends and colleagues. Duncan Lamont at one end of the spectrum, Evan Parker at the other. Very glad I caught both of those tours.
The original Incus ‘Song For Someone’ LP release is quite rare I think. There was a subsequent issue by Incus on thinner vinyl which is more obiquitous. The CD was put out by Evan Parker along with several other choice Wheeler (new) issues at the time. Invaluable !