It comes of the Eupatrid System in the Ear before Qin Dynasty, that is the officials are nominated by the King, and the official positions are descendent.
He began playing first half-crown stakes, and then higher and higher, till he became very rich, got an appointment in India, and rose to be Governor of Madras.
While a politician didn't absolutely have to be a certain age to run for office, or even to hold the office, previous office in the cursus honorum, exceptions were very few.