I have checked the civil registration index for 1965/1966 and 1967, if the death occurred in any county in England and Wales it will be registered and will show on the index. The name of the Registration District is given, each year is divided into 4 quarters that cover registrations in jan/Feb/.March, Apr/may/june; July/aug/sept; Oct/Nove/dec.
within each quarter the surnames are indexed alphabetically and within each surname, alphabetically by christian name. The age as given at time of registration is recorded for each entry. the district has a unique reference number followed by a letter, london is 1A, the further north the district the higher the refernece number. This reference is only valid for the national index at the General register office, local registration offices have a different number.