As I recall from the old Mark Ayres site, which has since disappeared, the sting was created in 1970 for the end theme edits that were done from the 1967 version of the theme. The best versions that can be found are literally tacked onto the 70s end themes. The end themes were of three different lengths as I recall. 40 seconds, 52 seconds and 1 minute 12 seconds, and the sting at the beginning lasted 3 seconds. They were blended in well so getting a clean version, other than through the official Radiophonic Workshop archivist, who is Mark Ayres, may be difficult, if not impossible.