When the HMS Teazer is sent to the West Indies, it leaves a sailor behind in London: seaman Ben Jackson, who has been given six months of shore posting in barracks and is quite depressed about it. Ben spends his free time moping at a nightclub called the Inferno for a week, until Polly, on assignment to cheer him up, gets him drawn into WOTAN's attack on London. When the matter of the War Machines has finally been cleared up, Ben is all set to return to barracks, but Polly persuades him to wait long enough for them to return the Doctor's TARDIS key. When they slip into the TARDIS to find the Doctor, it dematerializes and whisks them away from their proper time and place.
Not that Ben believes it, of course. Initially, he will at most believe that the TARDIS is some kind of strange instantaneous transport, but it takes an encounter with seventeenth-century pirates to convince him that the ship can actually travel in time, as well! Once he has become accustomed to it, Ben finds that he likes time travel, although he remains concerned about getting back to his ship (which he has apparently forgotten had departed for the West Indies without him!).
Ben is inherently very trusting of people (although highly suspicious of strange circumstances like time travel and regeneration) - he strikes up a friendship with Polly quickly, and he has barely met the Doctor before they become practically inseparable. And once he has made a friend, he remains very devoted to them, even willing to fight on their behalf. He is a very sensitive person, and finds it abhorrent to kill anything, even a creature as evil as a Cyberman. Perhaps due to his time in the military, he knows some martial arts, and is quick to defend his friends.
New experiences with the Doctor do startle Ben, and sometimes he works himself up into a panic over a terrifying encounter with alien creatures or human evildoers. The Doctor provides a stabilizing influence, and Ben is extremely confident in his abilities. However, he never quite loses his initial skepticism in the wonders of travelling with the Doctor, and he undergoes another crisis of faith when confronted with regeneration.
Ben is a good-looking young man with a wide smile and an immediately likable face. He is of average height, with light brown hair. His Cockney accent betrays his London roots and also cements his image as a "down to Earth" kind of person (except in the sense where he's often not actually on the Earth!). Like Dodo before him, Ben is fond of colloquialisms like "bird" and "bloke". There initially seems to be some attraction between him and Polly, although once they begin their travels in the TARDIS, this matures into a warm friendship, and their relationship has never spawned the same level of post-departure marriage speculation as that of Ian and Barbara. Nevertheless, it remains a distinct possibility. (Perhaps if he had come up with more plans involving Polly's cardigans...) Initially Ben wears his sailor uniform, but soon changes to more comfortable shirts and trousers. He likes to carry a Swiss Army knife around with him, which sometimes comes in very handy.
When the TARDIS brings Ben and Polly back to London in 1966, Ben realizes that has been given a chance to catch his ship. Although sad to part company with the Doctor, he is nevertheless glad to back in his own country and time, and so he and Polly say goodbye to TARDIS travel and return to their own lives.
