The South American guitar music heard during the end credits was played by John Williams, the virtuoso classical guitarist.
Donald Churchill, who plays Scott Eccles here, had played Dr. Watson in the 1983 TV adaptation of The Hound of the Baskervilles (1983).
The oddity that everyone seems to continuously refer to Holmes client by his full name is caused by an omission in the screenplay and the credits. He is John Scott-Eccles in the original short story, not Scott Eccles. Hence, he would be addressed as "Mr. Scott-Eccles" just as one would address John Rhys-Davies as "Mr. Rhys-Davies."
During an early conversation with Holmes, Watson refers to '...that most grotesque affair of the five orange pips...'. The Five Orange Pips was the fifth of the fifty-six short stories written by Conan Doyle, but was never turned into a Sherlock Holmes episode by Granada Television.
Another poster states that the full name of Scott Eccles was John Scott-Eccles. This is wrong. In the original short story he is named as 'John Scott Eccles' (no hyphenated surname), so it is perfectly feasible to refer to him using one or both of his first two names, however in his initial telegram to Holmes the writer refers to himself as 'Scott Eccles'.