From the British TV series
Yes, Prime Minister
PoD here in the Yes, Prime Minister verse is that Callaghan calls a snap election for 1978 and wins narrowly, thus forcing Margaret Thatcher to resign as Tory Leader. She is succeeded by Shadow Foreign Secretary Herbert Attwell (the unseen but named predecessor of Hacker in the show) who leads the Tories to a victory in the October 1981 general election.
Hacker, who was Shadow Agriculture Minister under Thatcher, ran the leadership bid of Shadow Education Secretary Martin Evans, who was defeated by Attwell. Hacker was retained in his role under Attwell in opposition but shifted to run the Ministry of Administrative Affairs after the 1981 election win. When Attwell resigns just over two years later due to health issues, Hacker succeeds him in an unopposed ballot after utilising knowledge of scandals behind Chancellor of the Exchequer Eric Jeffries and Foreign Secretary Duncan Short to force them out of the leadership running.
Hacker goes on to govern as a moderate, centre-right style Conservative and wins a general election in May 1986. He leads the UK through the end of the Cold War and emerges in the aftermath as a respected international statesman, particularly through negotiation of the fates of Eastern European breakaway states following the fall of the USSR, and taking a new foreign policy leadership role in the EU. He also oversees a series of well-received domestic reforms in education, local government and health, though his plans for radical defence policy and employment reform are thwarted throughout. The UK under the Hacker government encountered economic trouble towards the end of the Eighties which was a contributing factor in Hacker losing the 1991 election to John Smith's Labour Party.