In answer to your query about the theme music, I have checked The
Onedin Line single and also the reference to the music in the Radio
Times Onedin Line magazine.
The recording is by The Vienna Philharmonic Orchestra conducted by
Aram Khachaturian and is adapted by Anthony Isaacs.
Copies of the single are still available from various sources i.e.
eBay, specialist record shops, etc. It is a Decca release copyright
1971 – reference ZDR 50509/F 13259