Sir Humphrey Appleby (Nigel Hawthorne) starred throughout the series as permanent secretary under the direction of his minister Jim Hacker in the Administrative Affairs Department. He was appointed cabinet secretary, just as Hacker`s party entered a leadership crisis, and played an important role in Hacker`s rise to prime minister. It is committed to maintaining the status quo for the country in general and for the public service in particular.  Sir Humphrey was a master of concealment and manipulation, stunned his opponents with jargon and long-term rewrites, strategically appointed allies into supposedly impartial bodies, and set up interdepartmental commissions to stifle his minister`s bureaucratic proposals. The Right Honourable Jim Hacker MP (Paul Eddington), who was eventually raised at the House of Lords as Lord Hacker of Islington, was editor of a newspaper called Reform before getting into politics. He spent a lot of time in Parliament on the opposition benches before his party won a general election. In Yes`s minister, he was minister of administrative affairs (a fictitious ministry of the British government) and cabinet minister, and in Yes he became Prime Minister of the United Kingdom. Hacker graduated from the London School of Economics (a third-party graduate), for which he is often mocked by Oxford-educated Sir Humphrey (who attended Baillie College), a reference to the real Balliol College, which ended with a First in Classics. His former character is that of a politician, but naïve, which leads to significant changes in his ministry.
Soon, hackers noticed that public service tactics prevented its planned changes from being implemented. When he learns, he is spared and cynical by using some of the civil servants himself. While Sir Humphrey held all the aces at first, hacker occasionally plays his own asset. Much of the show`s humour therefore derives from the antagonism between cabinet ministers (who think they are in charge) and members of the British civil service (who think they really run the country). A typical episode focuses on Hacker`s proposal and the pursuit of reform and blocking Sir Humphrey from all hacking approaches. In most cases, Sir Humphrey prevents him from achieving his goal, while helping the hackers with positive publicity, or at least a way to cover up his failure. Sometimes, however, hackers get by, often by thwarting other arrangements or deals that Sir Humphrey has made elsewhere with other ministers or officials – or, in the case of the episode “The Tangled Web “, hackers successfully blackmail Sir Humphrey to adopt his position.