Patrick Troughton's tenure as the Doctor wasn't known as 'The Monster Years' for nothing. All manner of rubber-suited nasties shuffled across the screen between 1966 and 1969.
Usually, they were intent upon breaking into scientific bases accompanied by large amounts of foam. However, one of the Second Doctor's best-loved monsters has to be the Yeti. Rather than directly exploit the myth of the Abominable Snowman, writers Mervyn Haisman and Henry Lincoln opted to make the creatures robotic pawns of nebulous alien being the Great Intelligence.
Like many good Doctor Who monsters, the Yeti possessed an endearing gimmick - their little control spheres. If the sphere became separated from its host, it would roll across the floor in an attempt to return, all the time making a distinctive whistling sound easily imitated by children throughout the playgrounds of Britain.
Unsurprisingly, filming for the story didn't take place in or near Tibet. Snowdonia, North Wales, stood in for the Himalayas. Patrick Troughton was no doubt pleased to be snugly wrapped up in an enormous fur coat on location. The coat (and the Yeti) reappeared in Doctor Who's 20th anniversary tale The Five Doctors.
Guest star for The Abominable Snowmen was Jack Watling, playing explorer Professor Travers. Not only a respected film and television actor, Jack was also Deborah Watling's Dad. The character was deemed popular enough to return, many years older, for swift sequel The Web of Fear. Sadly, Jack passed away in 2001.
Also regrettably, only episode two remains in the BBC archives, although a full soundtrack of all six episodes - linked by narration from Fraser Hines - was released by the BBC Radio Collection.