Buckinghamshire was a Member of Parliament (MP) in the Irish House of Commons for Portarlington from 1784 to 1790 and thereafter for Armagh Borough from 1790 to 1797.

He sat also in the British House of Commons for the rotten borough of Bramber in 1788, a seat he held until 1790, and then for Lincoln from 1790 to 1796.

In 1798 he was recalled to England by the President of the Board of Control responsible for Indian affairs, Henry Dundas[3] and summoned to the House of Lords through a writ of acceleration in his father's junior title of Baron Hobart.

"[1] He was Chancellor of the Duchy of Lancaster in 1805 and again in 1812, Postmaster General from 1806 to 1807 and President of the Board of Control, a post for which his time in India suited him,[4] from 1812 to 1816.

Two years earlier William Pitt the Younger had broken off what was generally believed to be an informal engagement to Eleanor.