At college [Pitt Crawley's] career was of course highly creditable. And here he prepared himself for public life, into which he was to be introduced by the patronage of his grandfather, Lord Binkie, by studying the ancient and modern orators with great assiduity, and by speaking unceasingly at the debating societies. But though he had a fine flux of words, and delivered his little voice with great pomposity and pleasure to himself, and never advanced any sentiment or opinion which was not perfectly trite and stale, and supported by a Latin quotation; yet he failed somehow, in spite of a mediocrity which ought to have insured any man a success. He did not even get the prize poem, which all his friends said he was sure of.
After leaving college he became Private Secretary to Lord Binkie, and was then appointed Attache to the Legation at Pumpernickel, which post he filled with perfect honour, and brought home dispatches, consisting of Strasburg pie, to the Foreign Minister of the day. After remaining ten years Attache (several years after the lamented Lord Binkie's demise), and finding the advancement slow, he at length gave up the diplomatic service in some disgust, and began to turn country gentleman.
He wrote a pamphlet on Malt on returning to England (for he was an ambitious man, and always liked to be before the public), and took a strong part in the N**** Emancipation question. Then he became a friend of Mr. Wilberforce's, whose politics he admired, and had that famous correspondence with the Reverend Silas Hornblower, on the Ashantee Mission. He was in London, if not for the Parliament session, at least in May, for the religious meetings. In the country he was a magistrate, and an active visitor and speaker among those destitute of religious instruction. (9.9-11)
Sure he's boring and self-satisfied, but Pitt is one of the only characters in the novel whose ambition has very little to do with marriage. He is purely career minded throughout the book, and as we learn, he does actually have quite a bit of diplomatic and managerial skills. He ends up being a very successful estate owner, improving Queen's Crawley and getting ahead in parliament.