Baskerville was the richest man on Earth around 2010, having earned his money as an arms dealer. Having faked his death, he pretended to be a time traveller so that he could gain access to the ULTRA supercomputer (Claiming that he needed it to calculate a return journey to his time) while offering to sell his time machine. To reinforce his image as a time traveller, he "predicted" the outcome of a football game (by paying off the players to score precisely when and who he wanted) and the death of a young actress (with a secret fast-acting poison), and destroyed Athens by artificially creating a tidal wave. However, his fourth prophecy — the destruction of Tokyo with a malfunctioning nuclear warhead scheduled to be used for demolitions — was averted by the Eighth Doctor and Malady Chang.
His true plan was to use ULTRA to take control of the global markets by setting up a system where all of Earth's money was routed through his account, making all financial transactions impossible without Baskerville's approval, but he was interrupted before he could enter his account details into the final program, allowing the Doctor to enter his own account details instead and prevent Baskerville completing his plan.
When the Onihr attempted to interfere and acquire Baskerville's time machine for themselves, Fitz was able to trick them into taking Baskerville prisoner and take him back to their planet after the destruction of their ship. (PROSE: Trading Futures)