James "Jimmy" Jackson was the father of Ben Jackson.
In February 1942, he was a British soldier stationed in Singapore. His friends in the army referred to him as "Jacko". (AUDIO: The Forsaken) His son Ben was born in December of that year. (PROSE: Invasion of the Cat-People, AUDIO: The Forsaken)
After the war, he worked on a ship. In 1956, his son Ben was offered a job on board the same ship by the captain. (PROSE: Invasion of the Cat-People)
Before Ben began travelling with the First Doctor, James died of a heart attack. (AUDIO: The Yes Men)