Very occasionally — OK, once — a great TV series has even grown out of a lousy movie. Take a bow, Buffy the Vampire Slayer.

Successful TV series that spawned successful movies, on the other hand, are a rarer species, although there are a few notable examples: The Untouchables (which interestingly, was re-adapted back into a 1993 TV series that ran for two seasons), The Fugitive, Mission: Impossible and Serenity, a continuation of the much-loved Firefly. But Police Squad!, the short-lived series that led to The Naked Gun — which is on Comedy Central tonight — and its two sequels, belongs in a category of one.

I can’t think of another series that flew so low under most people’s radar when it was originally broadcast, yet spawned a hugely popular and profitable big-screen franchise.

I first heard of Police Squad! in journalism college. A first-year newbie, who’d been to the US in the summer, raved about this brilliant spoof cop show he’d seen on TV there.

Months later, without any fanfare, UTV began showing the series — which, of course, starred Leslie Nielsen as the idiotic Sgt Frank Drebin — in a teatime slot.

It was hilarious. The opening titles — which perfectly parodied old cop shows, right down to an anachronistic “In Color” — were, in themselves, small works of comedy genius. A recurring gag was the introduction of a “special guest star” — usually a well-known face like William Conrad, William Shatner and Lorne Greene — who was immediately murdered and never appeared in the actual episode.

Neither did Abraham Lincoln-impersonator Rex Hamilton, who was nonetheless shown every week firing back at his assassin, John Wilkes Booth.

Each episode had two titles, the one that appeared on screen and a completely different one announced by Hank Simms, the familiar voice from the opening titles of numerous Quinn Martin series of the 1960s and 1970s.

Aside from Nielsen, the only cast members who appeared in both the series and the movies were Ed Williams, as scientist Ted Olsen, and seven-foot-tall basketball player Ronald “Tiny Ron” Taylor as detective Al, whose head always towered out of shot.

Alan North played Drebin’s boss Captain Hocken, a role taken by George Kennedy on the big screen.

Mission: Impossible regular Peter Lupus played Officer Norberg, who was renamed Nordberg for the movies and played by OJ Simpson.

Episodes ended with a fake freeze-frame. The actors simply stood motionless while everything else kept moving: coffee being poured, a convict escaping, a chimpanzee throwing papers around in the background.

Police Squad! offers the same riotous mix of deadpan acting, daft plots, non sequiturs, slapstick, rapid-fire sight gags and pitch-perfect parody as the later movies, only in miniature.

Coming from the Zucker-Abrahams-Zucker team, who two years earlier had scored a massive success with Airplane!, which was where Nielsen first displayed his gift for comedy, Police Squad! should have been a huge hit.

But despite rave reviews from the critics, only six episodes were made. Just four had been shown when the ABC network cancelled the series. The reason given by the network’s president, Tony Thomopoulos, has gone down in television history as the stupidest ever.

“The viewers had to watch it in order to appreciate it,” he said. In other words, they actually had to pay some attention. That says a lot about what US TV networks thought of their audience.

All episodes of Police Squad! Are available on YouTube. The Naked Gun is on Comedy Central at 9pm tonight (May 6).