Verity Lambert and David Whitaker's carefully created characters blended into the perfect Tardis crew. Two aliens. An adolescent unearthly child whose only family was apparently this crotchety old man she called "grandfather". Then there were the two humans, who gave us the Earth point of view. Both Ian and Barbara were intelligent; well, by our standards anyway. Their knowledge was used to a great extent during their time with the series. Ian was undoubtedly the hero, protecting the other three against danger. But it was the Doctor who had the real intelligence and perceptiveness. Barbara had the gentle, feminine touch without being one of the naive variety.

Sadly, the alien side of her nature was not developed by the producers (save for a telepathic exchange with the Doctor in The Sensorites) and this led to the actress' decision to decline a new contract.

Susan left when she found love and had to choose whether to stay with her grandfather or to stay on post-Dalek Earth with David Campbell. The Doctor made the decision for her by locking her out of the Tardis explaining that she had to live her own life.

She always seemed more human than most Time Lords we have seen so she would have settled down well as Susan Campbell. But what will happen when she regenerates? Will she learn to time travel? Will the Doctor meet her again in "another world, another time"? Or is the power of regeneration not a birthright but an academic achievement?

Whatever the answers, Susan will remain one of the most enigmatic characters in the programme's history, rather like the rest of her family.

Steven Taylor was an astronaut who was in dire straits when his spacecraft crashed and he was held prisoner by the inhabitants of the planet Mechanus - the Mechanoids. He was something of a brawny hero, but lacked Ian's intelligence. When wounded during the attack on Troy, a pretty handmaiden comes to his aid - Katrina (played by Adrienne Hill). Her simple mind just could not comprehend the high technology of the Tardis when she re-paid their kindness by sacrificing her life to save them. Maybe, in dying, she finally reached "the palace of perfection" she sought, after all.

Katrina wasn't the only companion lost in that infamous time - the twelve weeks of the Dalek Master Plan. Sara Kingdom (played by Jean Marsh) was a ruthless and dedicated secret agent for the treacherous Guardian of the 41^st century solar system, Mavic Chen. Such was her dedication she even killed her own brother, Bret Vyon. However, when she saw what Chen was intending - to aid the Daleks in building a time destroyer - she changed sides. Her fate was sealed. She became the victim of the terrible weapon as she aged hundreds of years. Sara could have been a nice departure from the screaming schoolgirls style of companion, but alas, it was not to be.

"And doesn't she scream like Susan?" said the producers.

"And doesn't her name sum her up?" said the public.

Yet despite appearing in only five adventures, she is remembered; for these stories included the unforgettable Celestial Toymaker and the infamous Gunfighters.

In The Savages Steven left to lead a tribe of primitives. And in the next story, The War Machines, Dodo was returned to London.

Abandoning the schoolgirl image, incoming producer Innes Lloyd decided that he wanted to go for the dolly-bird look to attract the Dads. Polly was a vivacious, attractive blonde with blue eyes and a splendid figure. She was well matched with Ben Jackson, a cockney merchant seaman who was used to obeying orders by his training, hence he became one of the most loyal and resourceful companions for the Doctor. Polly was used to being protected and Ben was very much her protector as well as potential boyfriend. It was a well balanced swinging sixties image. But all that was to change.

Jamie's friendship with the Doctor was based on a deep understanding and mutual trust. He developed from a boy in The Highlanders to being very definitely a man who could look after himself by the time he left.

To the orphaned Victoria Waterfield Jamie wasn't only brave, but positively macho in defending one of the most beautiful girls ever to inhabit the Tardis. It was Victoria's lack of experience that was her most engaging quality. "Did you see how these lassies were dressed?" Jamie would tease her, like in The Ice Warriors. Because in the 19^th century not only was there no such thing as sexual equality, but women's legs were to be hidden at all times.

Jamie took a keen pleasure in all that went on around him, often sceptical about the Doctor's vague attitude to life, but ultimately he relished the challenge of the lifestyle the Doctor offered.

While Zoe may have left the Doctors side eventually (after all, her intelligence was more than a match for the Doctors), it is unlikely Jamie would ever have left his side. Hence it was appropriate that he was forced to leave by the Time Lords who returned Zoe to the Wheel in Space (the scene of her first adventure) and Jamie to Scotland 1746. And it is a great shame to see them returned without memory of all they had learned on their subsequent travels. Also, given the history of the Jacobite uprising, it is poignant that Jamie would either have been killed on his return or shipped off to a foreign country as part of the Highland clearances (which was part of the systematic destruction of the clan system in Scotland).

While Americans may not have been too overjoyed by the companion who represented them in the eighties, no-one can dispute that Jamie was a true Scot, and the characters seems to be as well remembered today as Patrick Troughton's Doctor is himself.

One of the other changes from this point forward was that the Doctor's companions would be called assistants, and for the next three years they couldn't really be called a "Tardis crew" given the Tardis was grounded on Earth. The UNIT family were on their way.