Jeremy Thorpe

Jeremy Thorpe was the Prime Minister of the United Kingdom, serving after Edward Heath. (PROSE: Interference - Book One) He was leader of the Liberal Party, which came to power as part of a broad coalition on a platform of social reform, the abolition of the death penalty, and a strong interstellar defence programme. (PROSE: The Devil Goblins from Neptune)

On one occasion, he had an adventure with the Third Doctor and decided that the Doctor's morality was dangerous. He recounted his experience into a tape recorder and ended the recording by saying that the Doctor must be stopped. (AUDIO: Damascus)

He was close to Global Chemicals. He personally forbade Brigadier Lethbridge-Stewart from investigating the company. (TV: The Green Death)

Thorpe was replaced as Prime Minister by Shirley Williams. (PROSE: Interference - Book One)

Behind the scenes

 * The Prime Minister was called "Jeremy" by the Brigadier, referencing Liberal Party leader . During production, there was a close-call general election; the Doctor Who production team, operating on the assumption that the UNIT stories took place in the near future, were joking that Thorpe (whose party was extremely unlikely to win) would be appointed Prime Minister.
 * Thorpe's forename wasn't given in Interference, but the common-sense interpretation of the passage is that the author was referencing Jeremy Thorpe.
 * He was explicitly mentioned in the "Party Politics" section of the BBC's Doctor Who site: "In the aftermath of several invasions of London in the late 60s, the 1970 election produces a hung parliament (conflicting Tory and Socialist policies towards the alien menace drive many voters towards the Liberals and fringe parties). In this atmosphere, a coalition government, led by Jeremy Thorpe, governs Britain in the early 70s." The article posits that continued alien invasions and "the power crisis caused by the collapse of Global Chemicals, the Government's involvement in the Axonite scandal and the Operation Golden Age fiasco, which included high ranking figures in the conspiracy" cause the coalition to collapse in 1973, and was succeeded by the Labour government under Shirley Williams.
 * He was played by Hugh Grant in the miniseries A Very English Scandal.