"Puppets without strings," jeered the critics, opting for the all too obvious witticism when faced with Gerry Anderson's unique and unsettling UFO. It's was a harsh, lazy judgement, for this is one of the best and most intriguing small screen fantasties.

1969's Doppelganger had found the Andersons shunning Supermarionation for live action cinema and now it was time to bring that experience to bear on television. UFO gave flseh, blood and humanity to the imaginative vision of Centruy 21, abandoning the charm of Thunderbirds and Joe 90 and heightening the bloodlust and edginess that had seemed so jarring in the sculpted, painted realty of Captain Scarlet. This was cold war fable, heady with paranoia, poisting a future world where Earth was under hidden threat from silent, bodysnatching extra-terrestrials.

There was more than a touch of The Invaders in the premise, but there was a cold, British unease in it execution that owed equally as much to the labyrinthine mysteries and cloaked dangers of Quatermass.

At heart, UFO was a thrilling clash between comic strip sensibilites and an unsettling adult cycnism. It shone with Matchbox Toy wonderment, of course, as every Anderson production does, but this was a series that dared to show the human cost of heroism.

SHADO Commander Straker lost his wife and son and still saved the world with cold-eyed professionalism. Sacrifices were made. People were exploited.  People died.  This was far from the chucklling fade-outs of Star Trek and in many ways foreshadowed the darkness of The X-Files.

It looked immaculate, glossy and clean, with feature film sheen. From the gleaming, saucers of the invaders to SHADO's missiles-nosed interceptors, Derek Meddings' visual effects remain a highly regarded example of shoestring budget work.

There were, however, purple wigs.