Joseph Roberts was a Jamaican man who emigrated to London in the first half of 20th century. He served in the Army during World War II and was injured during it. However, this injury also granted him a government pension, allowing him a decorous living in London.
In 1950s, he welcomed his nephew, Audrey Newman, and her husbad, Michael, in his house. He tried to reassure Audrey about the strange new behaviour of her husband, distant and cold (he was unaware that that Michael was actually a duplicate, created by anemone changelings).
When the TARDIS crashlanded near his house, he helped Steven Taylor and Sara Kingdom by giving shelter and repair to them and to the comatose First Doctor. He interceded with his landowner so he gives Steven and Sara a room, and when the Doctor disappeared, he helped Steven to find work at the same dock where Michael worked.
Two weeks later, when Billy Flint and other racists attacked his house he reproached Michael for doing nothing and went to stop them in his place. As he was confronting them, he suffered an heart attack and collapsed in the street. Steven came to help, and told Audrey to call an ambulance, which arrived swiftly and brought him to an hospital. Luckily, he recovered, and was on his way back to health when the awakened Doctor went to visit him in the hospital to thank him for his help. (AUDIO: An Ordinary Life)