The Master seemed to ponder for a moment before saying. "I don't think so. You see there has been a change of management while you were gone."
The Master looked to the painting on the wall. "If indeed this building was truly yours to begin with. The man in that painting seems a trifle more, dare I say pudgy and older than you do. Its quite possible you are from a parallel dimension to the one this city is from. And in any case this whole city has been moved from its home dimension to this world anyway. So even if you had a legitimate claim to the city and this building..."
The Master fixed him with a cold stare. "It is now null and void anyway. Possession is nine tenths of the law in almost all dimensions and worlds."
The Master came around the chair to stand in front of it and reaching into his pocket he pulled out his laser screwdriver which he had removed the Doctor's modifications turning it back into being a dangerous weapon. "As for who I am. You may call me the Master."