Jain, who is also the Director of the Vigilance department, had two offices - on the fourth and eighth floor of Delhi Secretariat.
From his eighth floor office, he has moved into Gamlin's office situated on the same floor due to her long absence.
"Jain has moved to Gamlin's office. The name plate of Gamlin placed outside her office has been replaced with Jain's name plate," sources said.
A tussle had erupted between the Delhi government and the Lt Governor over the appointment of Gamlin as the acting chief secretary in May by the latter which was opposed by the Arvind Kejriwal government which accused her of "lobbying for power distribution companies".