G is for... Gulliver

When the Doctor operated an emergency switch in the TARDIS to escape a volcanic eruption on the planet Dulkis, he warned his companions Jamie and Zoe that they would be taken out of Space / Time to a realm of which they knew nothing. After briefly visiting a mysterious white void, the ship appeared to break up and they were deposited in a world where characters from fiction were real. Hiding from Clockwork Soldiers in a forest of trees which spelled out proverbs and sayings, the Doctor encountered a man in 18th Century dress who spoke with a strong Nottingham accent. The stranger gave away their hiding places to the soldiers, but denied that he had seen anyone looking for them. After a couple of other encounters, the Doctor realised that the man was Lemuel Gulliver, from Jonathan Swift's Gulliver's Travels. He could only say lines which Swift had given to him.
It transpired that the TARDIS crew had been dumped into the Land of Fiction, controlled by a super-computer linked to the mind of an elderly English story writer. The computer wanted the Doctor to take the old man's place, whilst it had designs on taking over the Earth. Zoe overloaded the computer, causing it to be fired upon by its own robot guards, which destroyed the realm.
The Doctor pointed out that the characters they had met would come to no harm, as they were not real and would live on in fiction.

Played by: Bernard Horsfall. Appearances: The Mind Robber (1968).

• This was the first of Horsfall's appearances in Doctor Who - all in stories directed by David Maloney. He returned the following year as one of the Time Lord tribunal members in the final episode of The War Games, and was later seen as the Thal Taron in Planet of the Daleks. His last appearance was as Chancellor Goth in The Deadly Assassin - who may well have been the same Time Lord who had presided over the Doctor's earlier trial.
• Strangely, the Doctor expresses a hope to have a long chat with Gulliver some time. Strange - as the character would only be able to speak lines written for him in the book.