'The bottom of the North Sea is the home of a very strange creature,' warned Radio Times in January 1968.
'The gas being pumped out at high speed is its food', the BBC's magazine continued. 'The creature, disturbed and outraged by this human encroachment on its domain, makes its way ashore bent on vengeance.
'We are now – if you haven't already guessed – in the fantasy world of Dr. Who, and the creature is yet another monster for the Doctor and his companions to tackle.'
So readers were advised that shortly the Doctor, Jamie and Victoria would encounter the Fury from the Deep. This, the sixth story of Season Five (the series which also gave us classic monster tales like The Tomb of the Cybermen and The Ice Warriors) saw the debut of a new type of monster in Doctor Who.
As Radio Times went on to explain: 'The sea creature is being dreamed up by Jack Kine and his team in Visual Effects. For once it will not be based on an actor. Jack has found a new substance that fits the bill admirably. 'It is hard to describe,' he says, 'but you know the foam you see collecting on rivers at weirs? Well, imagine that five thousand times bigger.'
'Jack was experimenting with some a few weeks ago and in a very little time was able to get it to a depth of 30 feet. The creature is a bit like plasma – it starts in bits that gradually come together to form the final undulating beast. 'It's about the size of a first division football crowd!' says Jack.
'Before the advent of the seaweed creature, the idea was to keep Dr. Who's enemies as villainous and as mechanical as possible. Jack's boys look on the Doctor with mixed feelings, because in every story he finished by destroying the evil creatures and often wrecking their city – things that they spent weeks creating. 'Ah well,' says Jack, philosophically, 'I suppose the baddies must always lose.''