The series suffered from the BBC's lack of a proper archiving policy until 1978. It was BBC policy before 1978 to wipe master tapes and reuse them for other programmes, hence saving money and storage space. From a full tally of 799 editions, 466 (broadcast between 1962 and 1974) are thought to no longer exist; additionally, some colour videotaped episodes only survive as monochrome film copies. The final four series, broadcast between September 1974 and September 1978, exist in their entirety.
The "Z Cars" theme (traditional folk tune "Johnny Todd") proved to be so popular that Liverpool-based soccer side, Everton F.C, immortalized it as their theme tune as the teams enter onto the field, a tradition that is still very much alive today 45 years on. Elton John enjoyed the theme so much that he also adopted it at the club at which he presided as chairman, Watford.
In the early days the show was transmitted live, with only pre-shot film inserts to relieve the pressure for cast and crew. Mindful of the 14 million viewers about to tune in, Stratford Johns' nerves would regularly see him vomit before going into studio.
Troy Kennedy-Martin left the show when he felt that the Police were trying to influence storylines in their favour too much. He returned only to write Z Cars: Pressure (1978), the final edition in 1978 (which also saw the return of original director John McGrath and several early cast-members).
The famous Ford Zephyr fast response patrol cars were replaced with more up-to-date Pandas when the series was revived in March 1967. This reflected reality, as the Lancashire Constabulary (on which the Z Cars set-up had been largely based) had begun using them whilst the series had been off-air.
Elisabeth Sladen appeared in three episodes of the series. Producer Ron Craddock subsequently recommended her for the role of Sarah Jane Smith in Doctor Who (1963). She retained fond memories of the series, saying in 2009: "I loved Z Cars. If you see a clip of it now it still holds up incredibly well - really good actors, great directors, and flying by the seat of your pants. You kept on learning, and there were always places for you to learn, which there aren't so many of for young actors now."