UFO was a British television science fiction series created by Gerry Anderson and produced by Anderson's and Lew Grade's Century 21 Productions for Grade's ITC Entertainment company. Anderson had previously made a number of very successful marionette-based children's science fiction series including Stingray, Thunderbirds and Captain Scarlet. He had also made one live-action science fiction movie, Doppelgänger, also known as Journey to the Far Side of the Sun, and now felt ready to move into live-action television and aim at a more adult market.

UFO was Anderson's first series with live actors, but he had long experience with the one-hour format, good scripts, and exemplary production values. The show was aimed at children, but not exclusively, and also had broad appeal for teenagers, involving more realistic violence and remarkably 'adult' storylines.

UFO first aired in the UK in 1970 and in US syndication over the next two years. There were 26 episodes including the pilot, filmed over the course of more than a year, with a five-month production break caused by the closure of the show's original studio.

An idiosyncrasy of the series is that the term "UFO" is pronounced as a word ("you-foh") by the characters, and not as "you-eff-oh", as is more common with the acronym. This is particularly true of the lead character, Ed Straker. Technically speaking the series title should properly be pronounced "you-foh" as well. However, the "you-foh" pronunciation was not consistently applied and some supporting characters use the more traditional form.

In a sad coincidence, lead actors Ed Bishop and Michael Billington died in June 2005, within five days of each other.

The premise of the show is that in the near future (a fictional version of 1980) the Earth is under attack from aliens. Their spacecrafts can cross the vast distance between their planet and ours, but are only large enough to carry three or four aliens, and can only survive for a few hours in Earth's atmosphere before disintegrating or exploding. In flight they are surrounded by horizontally-spinning vanes and emit a distinctive pulsing electronic whine (actually produced by series composer Barry Gray on an Ondes Martenot). They defend themselves with laser-type weapons, but can be destroyed by conventional explosives. The alien ships can, however, survive underwater, and one episode deals with the discovery of a secret undersea alien base. The alien astronauts themselves are armed with machine gun-like weaponry that appear to shoot bullet-like projectiles.

Captured aliens are almost human in appearance but breathe a green oxygenated liquid, which is believed to cushion their bodies against the extreme acceleration of interstellar flight. To protect their eyes from the liquid the aliens wear opaque contact lenses with small pinholes for vision. After the autopsy of the body of a captured alien it is discovered that the body is, in fact, human and it is the ghoulish assumption that the aliens are controlling the dead bodies of abducted humans. The show's opening sequence begins by showing the (remarkable for the time) image of the removal of one of these lenses from an obviously real eye with a pair of forceps — a sight which upset some squeamish viewers.

To defend against the UFOs, a secret organisation called SHADO (Supreme Headquarters Alien Defence Organisation) is established. Operating behind the cover of the Harlington-Straker Studios movie studio in England, SHADO is headed by Commander Ed Straker (played by Ed Bishop), a former United States Air Force Colonel who poses as the studio's chief executive. In reality, this was a clever cost-saving move by the producers — the studio was the actual studio where the series was being filmed, originally the MGM-British Studios, later Pinewood Studios. Although the Harlington-Straker studio office block seen throughout the series was actually Neptune House - a building at the former British National Studios, in Borehamwood, that were owned by ATV.

Typical of Anderson productions, the studio idea was both practical and cost-effective for the production and a neat plot device. It removed the need to build an expensive exterior set for the SHADO base, while providing that all-important "secret" cover (concealment and secrecy are always central themes in Anderson dramas) with the trademark ring of plausibility. A studio was a business where unusual events and routines would not be noticed, and where comings and goings at odd times, the movement of vehicles, equipment, people and materiel would not excite undue interest and could easily be explained away as "sets", "props", or "extras".

A regular Anderson leitmotif was the concept of the mechanical conveyor — e.g., the automatic boarding tubes of Stingray and the Thunderbird craft. In UFO, this appeared in the guise of Straker's "secret" office, which doubled as a lift (elevator) that takes him down to the SHADO control centre located beneath the studio.

SHADO has a variety of high-tech hardware and vehicles at its disposal to implement a layered defense of Earth. Early warning of alien attack would come from SID (Space Intruder Detector), a computerized tracking satellite that constantly scans for UFO incursions into the solar system. The forward line of defence is MoonBase from which the three Lunar Interceptor spacecraft with nuclear missiles are launched. The second line of defense includes SkyDiver, a submarine mated with the submersible, undersea-launched Sky One interceptor aircraft which would attack UFOs in earth atmosphere. The last line of defense are ground units including the armed, tank-like SHADO Mobiles, fitted with caterpillar tracks. Special effects, as in all Anderson's marionette shows, were supervised by Derek Meddings.

The show's concept was very dark for its time — the basic premise was that the alien invaders are coming to collect human bodies to use as involuntary organ transplant donors. A later episode, "The Cat with Ten Lives", contains a particularly sinister plot point suggesting that the UFO pilots are not humanoid aliens at all, but are in fact human abductees under the control of the alien intelligences.

The show also featured realistic, believable relationships between the human characters to a far greater extent than usual in a typical science fiction series, showing the clear influence of American programs like The Twilight Zone and Star Trek and British action series such as Danger Man. One early episode clearly established an interracial romance between two continuing characters (something that was uncommon on British TV in those days), while others showed the heroes making mistakes with sometimes fatal consequences. And relatively few episodes of the series actually had happy or (for the characters) satisfying endings.

One especially dramatic episode " Confetti Check A-OK " is almost entirely devoted to the breakdown of Straker's marriage under the strain of maintaining his secret identity. Another, " A Question of Priorities " hinges on Straker having to make an agonising life-or-death choice — to rescue his critically-injured son by diverting an aircraft carrying SHADO mobiles to deliver life-saving medical supplies, or to attempt a last-chance intercept against an incoming UFO.

Another episode " The Square Triangle " includes a plot by a woman and her lover to murder her husband. When they accidentally kill an alien from a downed UFO instead, SHADO intervenes and doses the guilty pair with amnesia drugs. Straker realises the drugs will not affect their motivation, and SHADO cannot interfere without blowing its cover, and the end credits of this episode feature a very dark scene set in the future with the woman visiting her husband's grave.

Some critics complained that the emphasis on down-to-earth relationships weakened the show's science fiction premise and were also a means of saving money on special effects. The money-saving argument may have been true to a limited extent, but Anderson had always hoped to direct live action TV drama and although the marionette shows helped him develop impressive skills in effects and scripting, he had always considered them as essentially being a way of keeping in work and earning money while he tried to break into "real" TV. Others counter that the characters are more rounded than in other science fiction shows and that sci-fi concepts and special effects did not preclude realistic action and interaction and believable, emotionally engaging plots.

UFO confused broadcasters in both Britain and the United States who could not decide if it was a program for adults, or for children (the fact Anderson was primarily associated with children's programming did not help matters). This confusion — coupled with erratic broadcasts — are considered as contributing factors in its cancellation, although UFO is credited with opening the door to moderately successful runs of later live-action, adult-oriented programming by Anderson such as The Protectors and Space: 1999.

As with all the later Anderson series, the special effects, supervised by Derek Meddings, were of the highest quality and outstanding for their day, given the relatively limited resources at the team's disposal. The space sequences involving the Interceptors and UFOs are very well shot (showing the technical improvements that had come along since Kubrick's 2001: A Space Odyssey), with tight editing, fast action, and spectacular explosions.

In a clever refinement of the underwater effect developed for Stingray, Meddings' team devised a disconcerting effect — a double-walled visor for the alien space helmets which could be gradually filled from the bottom up with blue-dyed water. When filmed from the appropriate angle it produced a very convincing illusion of the helmet filling up and covering the astronaut's face.

After the 26 episodes were completed plans were drawn up for a sequel to be called UFO: 1999 which would have been set in a much bigger Moonbase. A subplot of the episode "Kill Straker!" sees Straker negotiating with SHADO's financial supporters for funding to build more moonbases within 10 years, which could be seen as a prologue to the UFO: 1999 concept. When American broadcasters dropped their support for a second season of UFO, the idea was dropped, but a couple of years later the concept was revised into an even more far-fetched story about the moon being blown out of orbit and Moonbase along with it — Space: 1999. Some of the uniforms worn by SHADO personnel would be recycled for the later series, and the Eagle spacecraft used in Space: 1999 were originally designed for UFO Year 2.

As with many Anderson productions, the series generated a range of desirable and well-executed merchandising toys based on the SHADO vehicles. The classic Dinky die-cast range of vehicles featured robust yet finely-finished products and included Straker's futuristic gull-winged gas turbine car, the SHADO mobile and the missile-bearing Lunar Interceptor. Like the Thunderbirds and Captain Scarlet related models, the original Dinky toys are now prized collectors items. All the major vehicles, characters, and more have been produced in model form many times over by a large number of licencee companies; the Anderson shows and their merchandise have always had widespread popularity, but they are especially popular in Japan.

The complete series has been released on DVD in the UK and in North America. Bonus features include a commentary by Anderson on the pilot episode "Identified", and an actor's commentary by Bishop on the episode "Sub-smash". There are also some deleted scenes and lots of stills and publicity artwork.

- From Wikipedia