The Liquidator

In this 1965 spy comedy-thriller, Rod Taylor plays Brian Ian "Boysie" Oakes, a bumbling tank corps sergeant who unwittingly shoots and kills two men attempting to assassinate British Intelligence Major Trevor Howard's character, Mostyn. Twenty-one years later, Mostyn recruits Oakes into MI5 as a paid assassin, code-named "Liquidator," but Oakes secretly hires a freelance contract killer to do the dirty work. As Oakes navigates his new role, he falls for Mostyn's secretary Jill St. John, while also facing off against enemy agents and a complex web of espionage.