Shirley Williams

Shirley Williams was the Prime Minister of the United Kingdom.

Williams was Prime Minister after Jeremy Thorpe. (PROSE: Interference - Book One)

During the Zygon gambit, the Prime Minister called Brigadier Lethbridge-Stewart and told him that there was to be no public announcement and to take "discreet but resolute" action. (TV: Terror of the Zygons)

Mrs Williams appointed Robert Bertram as UNIT's new scientific advisor. He later convinced her that the Brigadier Lethbridge-Stewart and his men were plotting with aliens, and to let him use his pacification device during his concert. (PROSE: No Future)

While the Eighth Doctor said Williams serve between Thorpe and Margaret Thatcher(PROSE: Interference - Book One), she's replaced by Callaghan, another Labour Party minister, in 1976. (AUDIO: The Oseidon Adventure)

Behind the scenes

 * In Terror of the Zygons, the female Prime Minister is not named, and in the novels her forename was not given, but the common-sense interpretation of the passage is that the author was referencing Shirley Williams.
 * She was explicitly mentioned in the "Party Politics" section of the BBC's Doctor Who site: "The alien invasions continue, and with the power crisis caused by the collapse of Global Chemicals, the Government's involvement in the Axonite scandaland the Operation Golden Age fiasco, which included high ranking figures in the conspiracy, the government falls in early 1973, bringing the Labour party, with Shirley Williams as leader, back to power."
 * In the real world, Williams was a prominent politician - and was part of Callaghan's cabinet - but never served as Prime Minister or even as the Labour Party leader.