Jim owned a business in London where the Doctor stored alien tech for safekeeping, usually after disabling any dangerous devices. He and his brother, Midge, who had his own lost property office nearby by the tube on Baker Street, were involved with multiple incarnations of the Doctor.
A month after being stranded in 2020, Liv thought to remind the Eighth Doctor to visit him. Jim was upset the Doctor took so long. He suggested that the Doctor should have left the key to 107 Baker Street with him, rather than entrusting the property to Thomas Brewster.
The Doctor also lent Jim his Volkswagen Beetle, citing its high maintenance costs.
Jim was also involved with the Curator, who dropped in after the Eighth Doctor's visit to inquire what he had taken out from the inventory.
Midge later said that Jim was confused when he gave the item to the Doctor, as they had both been given instructions by the Twelfth Doctor to keep the items a distance of 1 mile apart. When the Doctor left, Midge explained to the Curator that this happened due to misfiled paperwork. (AUDIO: Lost Property)